observing in uv
TRANSCRIPT
Observing in UV
S N Tandon IUCAA
(For UV Club Caltech)August 4 2021
Plan of the talk
bull Scope of UV observationsbull Technical elements
Transmission in atmospheric gasesMaterials for UV DetectorsNeed for contamination control
bull About ASTROSAT
bull UVIT TelescopeConfigurationSpecifcationsDesignLimitations
bull Capabilities of UVITbull Illustrative results
Scope of UV Observations
bull Planets to far reaches of the univeres
bull Earth
bull Sun
bull Hot stars
bull Accretion on compact objects
bull Star formation in Galaxies
bull Observation of interstellar medium
bull Intergalactic material
EARTHndash SEEN BY IUE
httparchivestscieduiuegalleryearth-specgif
JUPITER AURORA
UV
VISIBLE
httpfusephajhueduwpbfigureswfpc2_medjpg
httpfusephajhueduwpbsci_nhhtml
SOLAR CORONA IN FUV
httpenwikipediaorgwikiImageSOHO_EIT_ultraviolet_corona_imagegif
MESSIER 2 GLOBULAR CLUSTER FUV amp NUV
GLOBULAR CLUSTER M2
VISIBLE GALEXNUV amp FUV
IONISED OXYGEN IN THE HALO OF GALAXY(QUASAR SPECTRUM)
httpfusephajhueduGraphicsscigraphHVC_specjpg
Atmospheric Transmission
bull Oxygen absorbs wavelengths lt ~ 250 nm
bull Ozone absorbs wavelengths from ~200 nm to ~300 nm
bull Nitrogen has only few bands of absorption between 200 nm and 120 nm
In laboratory work for wavelengths gt 120 nm
a nitrogen bag can be used around the optics
( Safety precautions are required while using N2)
Status of the STUDIO UV balloon mission and platformA Pahlera M Aringngermannb J Barnstedtc S Bouguerouaa A Colind L Contic S DieboldcR Duffardsectd M Embergera L Hankec C Kalkuhlc N Kappelmannc T Keiliga S Klinknera
A Krabbea O Jansonb M Lengowskia C Lockowandtb P Maiera T Muumlllere T RauchcT Schanzc B Stelzerc M Taherana A Vaerneusb K Wernerc J Wolfa
Materials
bull For transmitting elements
Fused Silica works for wavelengths gt~ 170 nm
For wavelengths gt120 nm Sapphire and fluorides are common materials
For wavelengths lt~ 110 nm transmitting optics is not used
bull Aluminium coated with a protective coating of thickness for constructive interference mirrors can be used for wavelengths gt~ 100 nm
Detectors
bull Solid State Imagers
Silicon CCDs
Solar Blind CCDs
bull Photon Counting Intensified Imagers
Far Ultraviolet Sensitivity of Silicon CMOS Sensors Michael W Davis Thomas K Greathouse Kurt D
Retherford and Gregory S
QE plot for a 2DdopedEMCCD with the five-layer FIREBall-2 AR coating
Shouleh Nikzad et al 2017
Manijeh Razeghi Antoni Rogalski 1996
HST F220W (Red Leak in the Filter)
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Plan of the talk
bull Scope of UV observationsbull Technical elements
Transmission in atmospheric gasesMaterials for UV DetectorsNeed for contamination control
bull About ASTROSAT
bull UVIT TelescopeConfigurationSpecifcationsDesignLimitations
bull Capabilities of UVITbull Illustrative results
Scope of UV Observations
bull Planets to far reaches of the univeres
bull Earth
bull Sun
bull Hot stars
bull Accretion on compact objects
bull Star formation in Galaxies
bull Observation of interstellar medium
bull Intergalactic material
EARTHndash SEEN BY IUE
httparchivestscieduiuegalleryearth-specgif
JUPITER AURORA
UV
VISIBLE
httpfusephajhueduwpbfigureswfpc2_medjpg
httpfusephajhueduwpbsci_nhhtml
SOLAR CORONA IN FUV
httpenwikipediaorgwikiImageSOHO_EIT_ultraviolet_corona_imagegif
MESSIER 2 GLOBULAR CLUSTER FUV amp NUV
GLOBULAR CLUSTER M2
VISIBLE GALEXNUV amp FUV
IONISED OXYGEN IN THE HALO OF GALAXY(QUASAR SPECTRUM)
httpfusephajhueduGraphicsscigraphHVC_specjpg
Atmospheric Transmission
bull Oxygen absorbs wavelengths lt ~ 250 nm
bull Ozone absorbs wavelengths from ~200 nm to ~300 nm
bull Nitrogen has only few bands of absorption between 200 nm and 120 nm
In laboratory work for wavelengths gt 120 nm
a nitrogen bag can be used around the optics
( Safety precautions are required while using N2)
Status of the STUDIO UV balloon mission and platformA Pahlera M Aringngermannb J Barnstedtc S Bouguerouaa A Colind L Contic S DieboldcR Duffardsectd M Embergera L Hankec C Kalkuhlc N Kappelmannc T Keiliga S Klinknera
A Krabbea O Jansonb M Lengowskia C Lockowandtb P Maiera T Muumlllere T RauchcT Schanzc B Stelzerc M Taherana A Vaerneusb K Wernerc J Wolfa
Materials
bull For transmitting elements
Fused Silica works for wavelengths gt~ 170 nm
For wavelengths gt120 nm Sapphire and fluorides are common materials
For wavelengths lt~ 110 nm transmitting optics is not used
bull Aluminium coated with a protective coating of thickness for constructive interference mirrors can be used for wavelengths gt~ 100 nm
Detectors
bull Solid State Imagers
Silicon CCDs
Solar Blind CCDs
bull Photon Counting Intensified Imagers
Far Ultraviolet Sensitivity of Silicon CMOS Sensors Michael W Davis Thomas K Greathouse Kurt D
Retherford and Gregory S
QE plot for a 2DdopedEMCCD with the five-layer FIREBall-2 AR coating
Shouleh Nikzad et al 2017
Manijeh Razeghi Antoni Rogalski 1996
HST F220W (Red Leak in the Filter)
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Scope of UV Observations
bull Planets to far reaches of the univeres
bull Earth
bull Sun
bull Hot stars
bull Accretion on compact objects
bull Star formation in Galaxies
bull Observation of interstellar medium
bull Intergalactic material
EARTHndash SEEN BY IUE
httparchivestscieduiuegalleryearth-specgif
JUPITER AURORA
UV
VISIBLE
httpfusephajhueduwpbfigureswfpc2_medjpg
httpfusephajhueduwpbsci_nhhtml
SOLAR CORONA IN FUV
httpenwikipediaorgwikiImageSOHO_EIT_ultraviolet_corona_imagegif
MESSIER 2 GLOBULAR CLUSTER FUV amp NUV
GLOBULAR CLUSTER M2
VISIBLE GALEXNUV amp FUV
IONISED OXYGEN IN THE HALO OF GALAXY(QUASAR SPECTRUM)
httpfusephajhueduGraphicsscigraphHVC_specjpg
Atmospheric Transmission
bull Oxygen absorbs wavelengths lt ~ 250 nm
bull Ozone absorbs wavelengths from ~200 nm to ~300 nm
bull Nitrogen has only few bands of absorption between 200 nm and 120 nm
In laboratory work for wavelengths gt 120 nm
a nitrogen bag can be used around the optics
( Safety precautions are required while using N2)
Status of the STUDIO UV balloon mission and platformA Pahlera M Aringngermannb J Barnstedtc S Bouguerouaa A Colind L Contic S DieboldcR Duffardsectd M Embergera L Hankec C Kalkuhlc N Kappelmannc T Keiliga S Klinknera
A Krabbea O Jansonb M Lengowskia C Lockowandtb P Maiera T Muumlllere T RauchcT Schanzc B Stelzerc M Taherana A Vaerneusb K Wernerc J Wolfa
Materials
bull For transmitting elements
Fused Silica works for wavelengths gt~ 170 nm
For wavelengths gt120 nm Sapphire and fluorides are common materials
For wavelengths lt~ 110 nm transmitting optics is not used
bull Aluminium coated with a protective coating of thickness for constructive interference mirrors can be used for wavelengths gt~ 100 nm
Detectors
bull Solid State Imagers
Silicon CCDs
Solar Blind CCDs
bull Photon Counting Intensified Imagers
Far Ultraviolet Sensitivity of Silicon CMOS Sensors Michael W Davis Thomas K Greathouse Kurt D
Retherford and Gregory S
QE plot for a 2DdopedEMCCD with the five-layer FIREBall-2 AR coating
Shouleh Nikzad et al 2017
Manijeh Razeghi Antoni Rogalski 1996
HST F220W (Red Leak in the Filter)
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
EARTHndash SEEN BY IUE
httparchivestscieduiuegalleryearth-specgif
JUPITER AURORA
UV
VISIBLE
httpfusephajhueduwpbfigureswfpc2_medjpg
httpfusephajhueduwpbsci_nhhtml
SOLAR CORONA IN FUV
httpenwikipediaorgwikiImageSOHO_EIT_ultraviolet_corona_imagegif
MESSIER 2 GLOBULAR CLUSTER FUV amp NUV
GLOBULAR CLUSTER M2
VISIBLE GALEXNUV amp FUV
IONISED OXYGEN IN THE HALO OF GALAXY(QUASAR SPECTRUM)
httpfusephajhueduGraphicsscigraphHVC_specjpg
Atmospheric Transmission
bull Oxygen absorbs wavelengths lt ~ 250 nm
bull Ozone absorbs wavelengths from ~200 nm to ~300 nm
bull Nitrogen has only few bands of absorption between 200 nm and 120 nm
In laboratory work for wavelengths gt 120 nm
a nitrogen bag can be used around the optics
( Safety precautions are required while using N2)
Status of the STUDIO UV balloon mission and platformA Pahlera M Aringngermannb J Barnstedtc S Bouguerouaa A Colind L Contic S DieboldcR Duffardsectd M Embergera L Hankec C Kalkuhlc N Kappelmannc T Keiliga S Klinknera
A Krabbea O Jansonb M Lengowskia C Lockowandtb P Maiera T Muumlllere T RauchcT Schanzc B Stelzerc M Taherana A Vaerneusb K Wernerc J Wolfa
Materials
bull For transmitting elements
Fused Silica works for wavelengths gt~ 170 nm
For wavelengths gt120 nm Sapphire and fluorides are common materials
For wavelengths lt~ 110 nm transmitting optics is not used
bull Aluminium coated with a protective coating of thickness for constructive interference mirrors can be used for wavelengths gt~ 100 nm
Detectors
bull Solid State Imagers
Silicon CCDs
Solar Blind CCDs
bull Photon Counting Intensified Imagers
Far Ultraviolet Sensitivity of Silicon CMOS Sensors Michael W Davis Thomas K Greathouse Kurt D
Retherford and Gregory S
QE plot for a 2DdopedEMCCD with the five-layer FIREBall-2 AR coating
Shouleh Nikzad et al 2017
Manijeh Razeghi Antoni Rogalski 1996
HST F220W (Red Leak in the Filter)
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
JUPITER AURORA
UV
VISIBLE
httpfusephajhueduwpbfigureswfpc2_medjpg
httpfusephajhueduwpbsci_nhhtml
SOLAR CORONA IN FUV
httpenwikipediaorgwikiImageSOHO_EIT_ultraviolet_corona_imagegif
MESSIER 2 GLOBULAR CLUSTER FUV amp NUV
GLOBULAR CLUSTER M2
VISIBLE GALEXNUV amp FUV
IONISED OXYGEN IN THE HALO OF GALAXY(QUASAR SPECTRUM)
httpfusephajhueduGraphicsscigraphHVC_specjpg
Atmospheric Transmission
bull Oxygen absorbs wavelengths lt ~ 250 nm
bull Ozone absorbs wavelengths from ~200 nm to ~300 nm
bull Nitrogen has only few bands of absorption between 200 nm and 120 nm
In laboratory work for wavelengths gt 120 nm
a nitrogen bag can be used around the optics
( Safety precautions are required while using N2)
Status of the STUDIO UV balloon mission and platformA Pahlera M Aringngermannb J Barnstedtc S Bouguerouaa A Colind L Contic S DieboldcR Duffardsectd M Embergera L Hankec C Kalkuhlc N Kappelmannc T Keiliga S Klinknera
A Krabbea O Jansonb M Lengowskia C Lockowandtb P Maiera T Muumlllere T RauchcT Schanzc B Stelzerc M Taherana A Vaerneusb K Wernerc J Wolfa
Materials
bull For transmitting elements
Fused Silica works for wavelengths gt~ 170 nm
For wavelengths gt120 nm Sapphire and fluorides are common materials
For wavelengths lt~ 110 nm transmitting optics is not used
bull Aluminium coated with a protective coating of thickness for constructive interference mirrors can be used for wavelengths gt~ 100 nm
Detectors
bull Solid State Imagers
Silicon CCDs
Solar Blind CCDs
bull Photon Counting Intensified Imagers
Far Ultraviolet Sensitivity of Silicon CMOS Sensors Michael W Davis Thomas K Greathouse Kurt D
Retherford and Gregory S
QE plot for a 2DdopedEMCCD with the five-layer FIREBall-2 AR coating
Shouleh Nikzad et al 2017
Manijeh Razeghi Antoni Rogalski 1996
HST F220W (Red Leak in the Filter)
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
httpfusephajhueduwpbsci_nhhtml
SOLAR CORONA IN FUV
httpenwikipediaorgwikiImageSOHO_EIT_ultraviolet_corona_imagegif
MESSIER 2 GLOBULAR CLUSTER FUV amp NUV
GLOBULAR CLUSTER M2
VISIBLE GALEXNUV amp FUV
IONISED OXYGEN IN THE HALO OF GALAXY(QUASAR SPECTRUM)
httpfusephajhueduGraphicsscigraphHVC_specjpg
Atmospheric Transmission
bull Oxygen absorbs wavelengths lt ~ 250 nm
bull Ozone absorbs wavelengths from ~200 nm to ~300 nm
bull Nitrogen has only few bands of absorption between 200 nm and 120 nm
In laboratory work for wavelengths gt 120 nm
a nitrogen bag can be used around the optics
( Safety precautions are required while using N2)
Status of the STUDIO UV balloon mission and platformA Pahlera M Aringngermannb J Barnstedtc S Bouguerouaa A Colind L Contic S DieboldcR Duffardsectd M Embergera L Hankec C Kalkuhlc N Kappelmannc T Keiliga S Klinknera
A Krabbea O Jansonb M Lengowskia C Lockowandtb P Maiera T Muumlllere T RauchcT Schanzc B Stelzerc M Taherana A Vaerneusb K Wernerc J Wolfa
Materials
bull For transmitting elements
Fused Silica works for wavelengths gt~ 170 nm
For wavelengths gt120 nm Sapphire and fluorides are common materials
For wavelengths lt~ 110 nm transmitting optics is not used
bull Aluminium coated with a protective coating of thickness for constructive interference mirrors can be used for wavelengths gt~ 100 nm
Detectors
bull Solid State Imagers
Silicon CCDs
Solar Blind CCDs
bull Photon Counting Intensified Imagers
Far Ultraviolet Sensitivity of Silicon CMOS Sensors Michael W Davis Thomas K Greathouse Kurt D
Retherford and Gregory S
QE plot for a 2DdopedEMCCD with the five-layer FIREBall-2 AR coating
Shouleh Nikzad et al 2017
Manijeh Razeghi Antoni Rogalski 1996
HST F220W (Red Leak in the Filter)
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
SOLAR CORONA IN FUV
httpenwikipediaorgwikiImageSOHO_EIT_ultraviolet_corona_imagegif
MESSIER 2 GLOBULAR CLUSTER FUV amp NUV
GLOBULAR CLUSTER M2
VISIBLE GALEXNUV amp FUV
IONISED OXYGEN IN THE HALO OF GALAXY(QUASAR SPECTRUM)
httpfusephajhueduGraphicsscigraphHVC_specjpg
Atmospheric Transmission
bull Oxygen absorbs wavelengths lt ~ 250 nm
bull Ozone absorbs wavelengths from ~200 nm to ~300 nm
bull Nitrogen has only few bands of absorption between 200 nm and 120 nm
In laboratory work for wavelengths gt 120 nm
a nitrogen bag can be used around the optics
( Safety precautions are required while using N2)
Status of the STUDIO UV balloon mission and platformA Pahlera M Aringngermannb J Barnstedtc S Bouguerouaa A Colind L Contic S DieboldcR Duffardsectd M Embergera L Hankec C Kalkuhlc N Kappelmannc T Keiliga S Klinknera
A Krabbea O Jansonb M Lengowskia C Lockowandtb P Maiera T Muumlllere T RauchcT Schanzc B Stelzerc M Taherana A Vaerneusb K Wernerc J Wolfa
Materials
bull For transmitting elements
Fused Silica works for wavelengths gt~ 170 nm
For wavelengths gt120 nm Sapphire and fluorides are common materials
For wavelengths lt~ 110 nm transmitting optics is not used
bull Aluminium coated with a protective coating of thickness for constructive interference mirrors can be used for wavelengths gt~ 100 nm
Detectors
bull Solid State Imagers
Silicon CCDs
Solar Blind CCDs
bull Photon Counting Intensified Imagers
Far Ultraviolet Sensitivity of Silicon CMOS Sensors Michael W Davis Thomas K Greathouse Kurt D
Retherford and Gregory S
QE plot for a 2DdopedEMCCD with the five-layer FIREBall-2 AR coating
Shouleh Nikzad et al 2017
Manijeh Razeghi Antoni Rogalski 1996
HST F220W (Red Leak in the Filter)
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
MESSIER 2 GLOBULAR CLUSTER FUV amp NUV
GLOBULAR CLUSTER M2
VISIBLE GALEXNUV amp FUV
IONISED OXYGEN IN THE HALO OF GALAXY(QUASAR SPECTRUM)
httpfusephajhueduGraphicsscigraphHVC_specjpg
Atmospheric Transmission
bull Oxygen absorbs wavelengths lt ~ 250 nm
bull Ozone absorbs wavelengths from ~200 nm to ~300 nm
bull Nitrogen has only few bands of absorption between 200 nm and 120 nm
In laboratory work for wavelengths gt 120 nm
a nitrogen bag can be used around the optics
( Safety precautions are required while using N2)
Status of the STUDIO UV balloon mission and platformA Pahlera M Aringngermannb J Barnstedtc S Bouguerouaa A Colind L Contic S DieboldcR Duffardsectd M Embergera L Hankec C Kalkuhlc N Kappelmannc T Keiliga S Klinknera
A Krabbea O Jansonb M Lengowskia C Lockowandtb P Maiera T Muumlllere T RauchcT Schanzc B Stelzerc M Taherana A Vaerneusb K Wernerc J Wolfa
Materials
bull For transmitting elements
Fused Silica works for wavelengths gt~ 170 nm
For wavelengths gt120 nm Sapphire and fluorides are common materials
For wavelengths lt~ 110 nm transmitting optics is not used
bull Aluminium coated with a protective coating of thickness for constructive interference mirrors can be used for wavelengths gt~ 100 nm
Detectors
bull Solid State Imagers
Silicon CCDs
Solar Blind CCDs
bull Photon Counting Intensified Imagers
Far Ultraviolet Sensitivity of Silicon CMOS Sensors Michael W Davis Thomas K Greathouse Kurt D
Retherford and Gregory S
QE plot for a 2DdopedEMCCD with the five-layer FIREBall-2 AR coating
Shouleh Nikzad et al 2017
Manijeh Razeghi Antoni Rogalski 1996
HST F220W (Red Leak in the Filter)
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
GLOBULAR CLUSTER M2
VISIBLE GALEXNUV amp FUV
IONISED OXYGEN IN THE HALO OF GALAXY(QUASAR SPECTRUM)
httpfusephajhueduGraphicsscigraphHVC_specjpg
Atmospheric Transmission
bull Oxygen absorbs wavelengths lt ~ 250 nm
bull Ozone absorbs wavelengths from ~200 nm to ~300 nm
bull Nitrogen has only few bands of absorption between 200 nm and 120 nm
In laboratory work for wavelengths gt 120 nm
a nitrogen bag can be used around the optics
( Safety precautions are required while using N2)
Status of the STUDIO UV balloon mission and platformA Pahlera M Aringngermannb J Barnstedtc S Bouguerouaa A Colind L Contic S DieboldcR Duffardsectd M Embergera L Hankec C Kalkuhlc N Kappelmannc T Keiliga S Klinknera
A Krabbea O Jansonb M Lengowskia C Lockowandtb P Maiera T Muumlllere T RauchcT Schanzc B Stelzerc M Taherana A Vaerneusb K Wernerc J Wolfa
Materials
bull For transmitting elements
Fused Silica works for wavelengths gt~ 170 nm
For wavelengths gt120 nm Sapphire and fluorides are common materials
For wavelengths lt~ 110 nm transmitting optics is not used
bull Aluminium coated with a protective coating of thickness for constructive interference mirrors can be used for wavelengths gt~ 100 nm
Detectors
bull Solid State Imagers
Silicon CCDs
Solar Blind CCDs
bull Photon Counting Intensified Imagers
Far Ultraviolet Sensitivity of Silicon CMOS Sensors Michael W Davis Thomas K Greathouse Kurt D
Retherford and Gregory S
QE plot for a 2DdopedEMCCD with the five-layer FIREBall-2 AR coating
Shouleh Nikzad et al 2017
Manijeh Razeghi Antoni Rogalski 1996
HST F220W (Red Leak in the Filter)
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
IONISED OXYGEN IN THE HALO OF GALAXY(QUASAR SPECTRUM)
httpfusephajhueduGraphicsscigraphHVC_specjpg
Atmospheric Transmission
bull Oxygen absorbs wavelengths lt ~ 250 nm
bull Ozone absorbs wavelengths from ~200 nm to ~300 nm
bull Nitrogen has only few bands of absorption between 200 nm and 120 nm
In laboratory work for wavelengths gt 120 nm
a nitrogen bag can be used around the optics
( Safety precautions are required while using N2)
Status of the STUDIO UV balloon mission and platformA Pahlera M Aringngermannb J Barnstedtc S Bouguerouaa A Colind L Contic S DieboldcR Duffardsectd M Embergera L Hankec C Kalkuhlc N Kappelmannc T Keiliga S Klinknera
A Krabbea O Jansonb M Lengowskia C Lockowandtb P Maiera T Muumlllere T RauchcT Schanzc B Stelzerc M Taherana A Vaerneusb K Wernerc J Wolfa
Materials
bull For transmitting elements
Fused Silica works for wavelengths gt~ 170 nm
For wavelengths gt120 nm Sapphire and fluorides are common materials
For wavelengths lt~ 110 nm transmitting optics is not used
bull Aluminium coated with a protective coating of thickness for constructive interference mirrors can be used for wavelengths gt~ 100 nm
Detectors
bull Solid State Imagers
Silicon CCDs
Solar Blind CCDs
bull Photon Counting Intensified Imagers
Far Ultraviolet Sensitivity of Silicon CMOS Sensors Michael W Davis Thomas K Greathouse Kurt D
Retherford and Gregory S
QE plot for a 2DdopedEMCCD with the five-layer FIREBall-2 AR coating
Shouleh Nikzad et al 2017
Manijeh Razeghi Antoni Rogalski 1996
HST F220W (Red Leak in the Filter)
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Atmospheric Transmission
bull Oxygen absorbs wavelengths lt ~ 250 nm
bull Ozone absorbs wavelengths from ~200 nm to ~300 nm
bull Nitrogen has only few bands of absorption between 200 nm and 120 nm
In laboratory work for wavelengths gt 120 nm
a nitrogen bag can be used around the optics
( Safety precautions are required while using N2)
Status of the STUDIO UV balloon mission and platformA Pahlera M Aringngermannb J Barnstedtc S Bouguerouaa A Colind L Contic S DieboldcR Duffardsectd M Embergera L Hankec C Kalkuhlc N Kappelmannc T Keiliga S Klinknera
A Krabbea O Jansonb M Lengowskia C Lockowandtb P Maiera T Muumlllere T RauchcT Schanzc B Stelzerc M Taherana A Vaerneusb K Wernerc J Wolfa
Materials
bull For transmitting elements
Fused Silica works for wavelengths gt~ 170 nm
For wavelengths gt120 nm Sapphire and fluorides are common materials
For wavelengths lt~ 110 nm transmitting optics is not used
bull Aluminium coated with a protective coating of thickness for constructive interference mirrors can be used for wavelengths gt~ 100 nm
Detectors
bull Solid State Imagers
Silicon CCDs
Solar Blind CCDs
bull Photon Counting Intensified Imagers
Far Ultraviolet Sensitivity of Silicon CMOS Sensors Michael W Davis Thomas K Greathouse Kurt D
Retherford and Gregory S
QE plot for a 2DdopedEMCCD with the five-layer FIREBall-2 AR coating
Shouleh Nikzad et al 2017
Manijeh Razeghi Antoni Rogalski 1996
HST F220W (Red Leak in the Filter)
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Status of the STUDIO UV balloon mission and platformA Pahlera M Aringngermannb J Barnstedtc S Bouguerouaa A Colind L Contic S DieboldcR Duffardsectd M Embergera L Hankec C Kalkuhlc N Kappelmannc T Keiliga S Klinknera
A Krabbea O Jansonb M Lengowskia C Lockowandtb P Maiera T Muumlllere T RauchcT Schanzc B Stelzerc M Taherana A Vaerneusb K Wernerc J Wolfa
Materials
bull For transmitting elements
Fused Silica works for wavelengths gt~ 170 nm
For wavelengths gt120 nm Sapphire and fluorides are common materials
For wavelengths lt~ 110 nm transmitting optics is not used
bull Aluminium coated with a protective coating of thickness for constructive interference mirrors can be used for wavelengths gt~ 100 nm
Detectors
bull Solid State Imagers
Silicon CCDs
Solar Blind CCDs
bull Photon Counting Intensified Imagers
Far Ultraviolet Sensitivity of Silicon CMOS Sensors Michael W Davis Thomas K Greathouse Kurt D
Retherford and Gregory S
QE plot for a 2DdopedEMCCD with the five-layer FIREBall-2 AR coating
Shouleh Nikzad et al 2017
Manijeh Razeghi Antoni Rogalski 1996
HST F220W (Red Leak in the Filter)
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Materials
bull For transmitting elements
Fused Silica works for wavelengths gt~ 170 nm
For wavelengths gt120 nm Sapphire and fluorides are common materials
For wavelengths lt~ 110 nm transmitting optics is not used
bull Aluminium coated with a protective coating of thickness for constructive interference mirrors can be used for wavelengths gt~ 100 nm
Detectors
bull Solid State Imagers
Silicon CCDs
Solar Blind CCDs
bull Photon Counting Intensified Imagers
Far Ultraviolet Sensitivity of Silicon CMOS Sensors Michael W Davis Thomas K Greathouse Kurt D
Retherford and Gregory S
QE plot for a 2DdopedEMCCD with the five-layer FIREBall-2 AR coating
Shouleh Nikzad et al 2017
Manijeh Razeghi Antoni Rogalski 1996
HST F220W (Red Leak in the Filter)
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Detectors
bull Solid State Imagers
Silicon CCDs
Solar Blind CCDs
bull Photon Counting Intensified Imagers
Far Ultraviolet Sensitivity of Silicon CMOS Sensors Michael W Davis Thomas K Greathouse Kurt D
Retherford and Gregory S
QE plot for a 2DdopedEMCCD with the five-layer FIREBall-2 AR coating
Shouleh Nikzad et al 2017
Manijeh Razeghi Antoni Rogalski 1996
HST F220W (Red Leak in the Filter)
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Far Ultraviolet Sensitivity of Silicon CMOS Sensors Michael W Davis Thomas K Greathouse Kurt D
Retherford and Gregory S
QE plot for a 2DdopedEMCCD with the five-layer FIREBall-2 AR coating
Shouleh Nikzad et al 2017
Manijeh Razeghi Antoni Rogalski 1996
HST F220W (Red Leak in the Filter)
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
QE plot for a 2DdopedEMCCD with the five-layer FIREBall-2 AR coating
Shouleh Nikzad et al 2017
Manijeh Razeghi Antoni Rogalski 1996
HST F220W (Red Leak in the Filter)
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Manijeh Razeghi Antoni Rogalski 1996
HST F220W (Red Leak in the Filter)
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
HST F220W (Red Leak in the Filter)
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Solar Blind Detectors Materials
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Limitations of Solid State Detectors
bull Red leakbull Read noise of a few electronspixel (IMPROVING)
Typical PSF would have ~ 10 pixels and photonrate could be ltlt 1(s pixel) except for very bright stars or very large telescopes
Exposure per frame should be gtgt 1 s and very good pointing is required
bull Good cooling for low dark current and hencegood contamination mitigation
bull Cosmic-ray generated Cherenkov showers contribute to the background ndash more later
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Photon Counting Detectors
bull CCDCMOS with read noise ltlt 1 ebull MCP intensifier based detectors are common
MCP has a grid of ~ 10 micron dia holesPhoto-cathode kept close (lt 05 mm) to MCPor deposited on MCP
MCP multiplies the photo-electron to a pulse of few million electrons
Position of the pulse detected by a grid of wires or converted to pulse of light for a CCD etc
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Photon Counting hellip
bull Spatial resolution Depends onCross drift of photo-electron(Depends on gap from MCP voltage drop to MCPand energy of the photonphoto-electron)Diameter of MCP holesMultiplication in MCPDetails of Wire grid or CCD etc Typically 20 - 50 microns
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Effective aperture 39 mm
512X512 PixOf 25 micron
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Limitations of Detectors for UVIT
bull Low QE ~ 5 at 130 nm
could be gt 10 for photo-cathode on MCP
bull Saturation
Multiple photo-electrons (in 10rdquo) in a frame
Local reduction of multiplication in MCP for
high rates of photo-electrons say gt 100s
bull Frame rate ~ 29s for full field max ~ 600s for partial field (~ 10^5 for Wire-grid readout)
bull Spatial resolution ~ 25 micron
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
The HST-COS Far Ultraviolet Detector Final Ground Calibration John Vallergaa Jason McPhatea Adrian Martina Geoff Gainesa Oswald
Siegmunda Erik Wilkinsonb Steven Pentonb and Stephaneacute Beacutelandb
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
About ASTROSATbull ASTROSAT is an Indian satellite for multi
wavelength astronomy with emphasis on High Energy Astronomy
bull For simultaneous observations there are four co-aligned telescopes 3 for X-rays and one for ultraviolet and one X-ray Scanning Sky Monitor
bull The three X-ray telescopes cover a range from 1 ndash 100 keV and the ultraviolet telescope (UVIT) covers a wavelength range 125nm to 300nm
bull The project started in 2004 and launch was on September 28 2015
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
LAXPCUVIT
SXT
CZT
SSM
Phased Array Antenna
Star Sensors
ASTROSAT
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
ASTROSAT-SPACECRAFT
bull Altitude 650 km
bull Inclination to Equator 8 deg
bull Mass 1500 kg (780 kg Payloads)
bull Power generated 1900 watts
bull PSLV launch from India
bull Launch September 28 2015
bull Operational life of minimum 5 years
bull Pointing error lt3rsquo and drift lt 05rdquos
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Current Status of ASTROSATbull Targets awarded time in ldquoA02 to A10rdquo cycles CZT
ndash 9 LAXPC-264 SXT-183 and UVIT-880
bull Targets observed till June 15 21 ldquo2215rdquo
bull Papers published ldquo132rdquo till March 2021 including instrumentation and pre-prints
bull Instrumentsrsquo status
CZT and SXT Fully Operational
LAXPC and UVIT Partly Operational
bull UVIT Status Of the two UV channels NUV failed in 2018 and now only FUV channel is operational
All the quality parameters for FUV are unchanged
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Wide field UV- Imaging Telescopes
bull Galex (decommissioned) Swift_UOT amp UVIT
bull Comparision of some key features
Galex UOT UVIT
Telescope 500 mm 300 mm Two ndash 375mm
Field 75rsquo dia 17rsquoX17rsquo 28rsquo dia
λ (nm) 134-179 125-180
177-280 gt 160 200-300
Multi-Filters NO Yes Yes
Slitless-Sp Yes NO Yes
Spatial Res 5rdquo 25rdquo 15rdquo
Zero point mag 188201 181198
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Collaboratoring Institutes for UVIT
bull Indian Institute of Astrophysics
bull Inter University Centre for Astronomy amp Astrophysics
bull Tata Institute of Fundamental Research
bull Many Centres of ISRO
bull Canadian Space Agency
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Configuration of UVIT
bull Two telescope of ~ 375 mm aperture
bull Simultaneous imaging of the field in 3 bands Far UV Near UV and Visible
bull Visible only for tracking drift of pointing every ~ 1 s
bull Mass ~ 200 kg
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
FUNCTIONAL SPECs of UVIT
bull SPECTRAL CHANNELS FUV NUV VIS
125-180 200-300 320-550 nm
bull FIELD OF VIEW ~ 28rsquo
bull Aperture of Telescopes 375 mm
bull SELECTABLE FILTERS for Part of the Band
bull SPECTROSCOPY (Slitless) ~ 100 res in FUVNUV
bull TEMPORAL RESOLUTION ~ 5 ms
bull OBSERVING MODE STARE
bull SENSITIVITY IN FUV mag 20 in 200 s
bull PHOTOMETRIC ACC lt 10
bull SPATIAL RESOLUTION FWHM lt15rdquo
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Design of UVIT
See the next few slides
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
UVIT- Configuration
BLACK BAFFLES TO MINIMISESTRAY LIGHT
DETECTORS and FILTERS
दढता
तापमान की सथिरता
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Focussing Optics
bull Pair of co-aligned Cassegrain Telescopes each of ~ 375 mm aperture with f12 beamUseful field ~ 30rsquo diaPlate Scale ~ 0025 mmarcsecTelescope 1 for FUV (125-180 nm)Telescope 2 for NUV (200 ndash 300 nm)
amp VIS (320-550 nm) Multiple filters for selecting part of the band in all
bull Structure made of Invar bull No focus adjustment in orbitbull VIS for only for tracking aspect every ~1 s
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Optics of UVIT
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
NUV Filters
Lyman Alpha Cut
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
FUV Filters (Uncoated)
Blocks 1304 nmOx line
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Detectors
bull Pointing of the SC drifts by gtgt 1rdquobull Track the drift on ~ 1 S time-scale (VIS band)bull Combine ltlt 1 S exposures by Shift and Addbull Faintest sources could give lt 0001 es
Thus the read noise should be ltlt 1 electron and Photon Counting detectors are neededDark current too should be ltlt 1s per PSF solar blind detectors with high work-function are convenient as these do not require cooling and red-leak is not an issue
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Effective aperture 39 mm
512X512 PixOf 25 micron
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
DETECTOR MODULECMOS-IMAGEREach 25 micron pixelis ~ 3rdquo x 3rdquo
Fibre-taper~ 3 1
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
bull Detectorsrsquo Performance
bull Spatial resolution ~ 25 microns ~ 1rdquo(Centroid of light pulse of FWHM ~ 1 pixel to get
accuracy of ~ 01 pixel for each photon)bull Distortions (due to fibre-taper) up to ~ 5rdquo
After correction with calibration ~04rdquo rmsbull Read rate ~ 29s for full and up to 600s for
partial framesbull Saturation due to multiple photons within 10rdquobull Saturation due to MCP impedance
lt5 for 150 CS for a point source
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Scattered Light from out of the Field
bull All direct light from out of the field is avoided
bull After one scatter Only for angles lt 10 deg
bull Scattering from optical surfaces are minimised by minimising micro-roughness
bull All the structures are inorganic-black treated
bull In the absence of any overlaying atmosphere this scattered light can be attenuated by very large factors
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Baffle system for UVIT
Main Baffle
M1M2
Telescope tube
Secondary baffle
Primary baffle
( + Sun-shield )
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Scattering processes
Scattering from mirrors
due to micro-roughness
Various scattering paths via baffle
large angle scattering small angle scattering
micro-roughness
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Comparing measured lsquoattenuation factorrsquo with calculations
Calculation micro-roughness 30 A reflectivity 5 amp 10
Measred Half size model with 2 mirrors of micro-roughness 30 A
26x10^9
70x10^8
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Contamination Control
bull This was an important global issue to be controlled in all the parts contained within structure of the telescope and for all locations of testing and assembly storage and transport and launch and in-orbit
bull For Far UV even a monomolecular layer of organics can reduce transmission a lot
bull Invisible devil took years to convince people that it was real devil and not imagination
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
What did it involve
bull Minimise use of plastics and test any plastic to be used
bull Avoid exposure to ultraviolet on gound and in the orbit
bull Isolate the telescopes with a door from the rest of ASTROSAT for the first 2 months in the orbit
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
What did it involve
bull A special clean laboratory was constructed at IIA between 2003 and 2008 for all testing and assembly activities
bull A lot of preparations were done at the different centres of ISRO too for this control
bull All the hard work at IIA and ISRO paid and if any contamination reduced the efficiency on ground it was lt 20 for Far UV and in 4 yrs of orbit by lt 3
bull If an ant had entered the telescope cavity
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
MGKM Clean Laboratory IIA
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Testing Materials Exposing MgF2 window to heated sample in vacuum
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Contamination-monitoring Coupon in centre of PM
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Purging of Focal Plane withNitrogen for Motor Lubrication
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Working in Class 1000 clean-room
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Calibrations
bull Photometric with HZ4
bull Flat field (Ideal scan with a standard star)
High frequency variations for the detectors calibrated on ground
Filters were checked on ground for lack of any variations of gt 5 on scale of few arcminutes
Low frequency variations checked in orbit with multiple exposures with shifts to a part of SMC
bull Distortion
On gd with a grid of holes kept close to window
In orbit with images of SMC
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
LimitationsComments on Observations
bull Safety factorsDoors closed till 2 months spent in the orbit to avoid
contaminationOpen doors act as sun-shield to minimise UV falling on PMBright Object Detected ndash Detectors OFF blind-filter
manual intervention for resetOptic axis-orbit tangent angle gt 10 degDetectors OFF during day of orbitSun angle gt 90 deg bright-earth angle gt 20 deg
Fast drift in the beginning due to drift of Gyros and sudden correction by Star Tracker --- in effect the PSF might have invisible tail and loss of exposure timebull Frames with Cosmic Ray Showers increase the background
(~ 150 eventss) but the frames can be discarded statistically
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Cosmic Ray Shower
PHOSPHOR
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Limitations hellip
bull As there is no active transmitting optics there are no ghosts
bull In some cases a bright streak is seen for NUV when a very bright object is present close to edge of the field
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Streak in M31 Image
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Limitations hellip
bull Saturation If gt 1 photon is detected in a frame within ~ 10rdquoX10rdquo (3X3 pixels of Star250) area these are detected as as single event
bull Thus a correction is required for any point sources which give gt 01 cframe
bull For bright sources it is best to observe with partial frames to get a higher rate of framessecond
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Limitations hellip
bull Filter for VIS band the filter should be selected such that the signal for the brightest star is within the desired limit (4800 eventss) and yet signals for the stars are not attenuated too much else tracking suffers
(For VIS band the detectors are used with low value of multiplication in MCP as the photon flux is high)
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
An early Image (NGC 2336) all frames added directly
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Image (NGC2336) with shift and add
5rsquo
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Capabilities of UVITbull Basic features
Imaging in FUVamp NUV with multiple filters and Slitless Spectroscopy (res ~ 100) in 28rsquo dia field
PSF FWHM lt 15rdquo
Low Dark Current 10-50 cs
Low Distortion over the field lt 04rdquo rms
Long term stability of effective areas
Thus good for Deep Imaging with long exposures and imaging of crowded fields
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Performance parametersbull Targets observed so far gt 800 bull Image QualitySpatial Resolution lt 15rdquo FWHMZero Point AB mag for FUV-Caf2 181
stable to lt 3 over 4 yearsZero Point AB mag for NUV-Silica 198Background FUV-CaF2 ~ 200 CSBackground NUV-Silica ~ 2500 CS Distortion in final images lt 04rdquo rmsFlat-field variation in the field lt 5 rmsExcept for NUV B15 filter
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Some Illustrative Results1 Good Spatial Resolution FWHM ~ 15rdquo
2 Low instrumental darknoise allows very long exposures for high sensitivity
3 Good linearity of scale (04rdquo on the full field) to match sources in crowded fields
4 Differential between filters to estimate bright emission lines
5 Spectral information Slitless spectroscopy
6 Temporal correlation X-ray and UV
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
mag 265 Galaxy at Z ~ 14 Emitting Ly-contKanak et al
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
NGC 40 Spectrum (N K Rao et al ) (Emision lines in FUV and NUV filters)
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
NGC 40 H2 CloudCredit N K Rao et al
CII line
Continuum
H2 cloud here
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
NGC 40 (N K Rao et al)
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
NGC 40 (N K Rao et al)
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
bull Fig 4 Cross-cuts in the images of the nebula in three filters F169Mbull (blue) F172M (green) and N219M (red) made along the white linesbull shown in the slightly smoothed F169M image of the nebula (top)
Crosscutsbull of 8 pixel widths were obtained in all the images at the samebull locations (coordinates) The bottom cross-cut which passes through thebull nebular core is on a logarithmic scale and has been smoothed We notebull the faint quasi-circular extended halo around the core of the nebula (onbull the south-east side) This region has been shown with a grey overlaybull in the plots Despite having similar core fluxes in all three filters onlybull F169M shows the presence of the halo
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
NGC 6302 ( N K Rao et al)
The side lob in F172 and in NCG 169
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Credit Annapurni
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
NGC 5466 with UVIT
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
NGC 5466 with Galex
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
NGC 5466 with UVITSnehlata Sahu et al
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Credit Deepthi et al
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Credit Deepthi et al
Longest period vEHBs are the weakest
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
NGC 7252 Atoms-for-Peace
Post-merger galaxy
Red shift ~ 00159
Distance ~ 68 Mpc
UVIT spatial resolution ~ 400 pc
UVIT integration time
NUV Silica ~ 7915s
FUV Silica ~ 8138s
Aim To study the spatial variation of star formation in the galaxy and the tidal tails
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
NUV image Star forming regions in the tidal tail are of dwarf galaxy size
NGC 7252 Atoms-for-Peace
(George Koshy et al)
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
NGC 7252 ldquoAtoms-for-Peacerdquo galaxy
(FUV-NUV colour map)
(George Koshy et al)The pixel colour map of
NGC7252 reveals a blue
circumnuclear ring of diameter
sim 10 (32 kpc) with bluer
patches located over the ring
Based on a comparison to
single stellar population models
we show that the ring is
comprised of stellar populations
with ages 1113088 lt 300 Myr with
embedded star-forming clumps
of younger age (1113088 lt 150Myr)Age contours of 150 (red) 250 (green) 300 (blue) Myr
George K et al AampA 613 L9 (2018)
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
UVIT FUV Exposure time ~ 15ks
FUV UVIT image of Jellyfish galaxy JO201
CreditGeorge Koshi
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Evidence for star formation quenching due to feedback from an active galactic
nucleus in a jellyfish galaxy undergoing strong ram pressure stripping
Cyan [FeVII]
JO201 AGN feedback
George et al MNRAS
UVIT NUV
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Measuring black hole spin of Fairall 9 with AstroSat UVX-ray spectroscopy G C Dewangan1 Shrabani Kumar1 I E Papadakis2 3 K P Singh4 and P
Tripathi1
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
UV spectrum
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Fitting UV-X-ray Spectra to Spin
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
bull AstroSatUVIT observations of IC 4329A Constraints on the accretion disc inner radius Gulab C Dewangan1 P Tripathi1 I E Papadakis23 and K P Singh4
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
NUV (left) and FUV Images
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Radial Fits to the Images(NUV left FUV right)
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
bull The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening as well as for the contribution of emission lines from the broad and narrow-line regions The intrinsic UV continuum emission shows a marked deficit compared to that expected from the standard models of the accretion disc around an estimated black hole mass of 1-2 times 108 M⊙ when the disc extends to the innermost stable circular orbit We find that the intrinsic UV continuum is fully consistent with the standard disc models but only if the disc emits from distances larger than sim80-150 gravitational radii
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
UVX-ray variability of AGN with AstroSat
NGC7469 ( Dewangan et al)
SXT
FUV
NUV
FUV leading X-rays
NUV leading X-rays
NUV leading FUV
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Some members from UVIT Team
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
THANKS
END of the talk
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Some References
AampA 609 L1 (2018)
httpsdoiorg1010510004-6361201732188copy ESO 2018
LETTER TO THE EDITOR
Astronomyamp
Astrophysics
Planetary nebulae with UVIT Far ultra-violet
halo around the Bow Tie nebula (NGC 40)
N Kameswara Rao1 F Sutaria1 J Murthy1 S Krishna1 R Mohan1 and A Ray23
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
bull Version of Record httpswwwsciencedirectcomsciencearticlepiiS0168900219312203
bull Manuscript_868c71a0622b9ca9f348f74b33553b5e
bull 1 Overview of spatial and timing resolution of event
bull 2 counting detectors with Microchannel Plates
bull 3 AS Tremsin JV Vallerga OHW Siegmund
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Observing with UVIT - more
bull PC mode and saturation due to gt 1 photon in a frame
bull Bright object avoidance
bull Sun Moon bright earth avoidance
bull Selection of filter in VIS
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Some Incidences
bull During the vibrations tests of the Engineering model the secondary mirror came loose
This was possibly due to less than full tightening of a bolt ndash it happened
The bolts were replaced by larger bolts
bull A primary mirror was found to have an unexpected aberration when tested at IIA after being passed by LEOS
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Some
This was a real surprise and had to be confirmed by multiple rounds of testing and many discussions between UVIT and Leos over several weeks
Actually in such instrumentation any unexpected observation takes long to resolve because it is examined from all possible angles
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Some
bull The VIS detector failed during the vibration test of the flight model -- in March 2013
Could not find any design fault for the failure and It took 2 years to get this fixed
bull A single point suspension of the flight model had a faulty bolt connection but was detected before it could lead to damage
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Making
bull Testing of each optical componentMirrors by LEOS and IIADetectors by CSA amp IIA and ISROFilters amp Gratings by IIAFilter wheel motors-drivers delivered by ISRO
bull Assembly amp Testing of individual telescopesTesting the mirror assembly alone next withthe filters and the detectors All in clean room of Class 1000 and tests of the full telescopes in vacuum chamber
bull Assembly of full instrument at IIA
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Making of UVIT-Time Line
bull 2002 Maximal configuration with FarUV and Near UV bands approved
bull 2003 Agreement between ISRO and CSA for development of the detectors
bull 2004 Formal approval of ASTROSAT project
bull 2015 September 28 launch of ASTROSAT
bull Near UV detector of UVIT failed in 2018 and
UVIT still making good images in Far UV
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
baffles
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Uncorrected Distortion FUV Detector
CMOS
PHOSPHOR
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Uncorrected Distortion NUV Detector
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Relative positions FUV and NUV
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Cosmic Ray Shower
CMOS
PHOSPHOR
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Cosmic Ray Shower
PHOSPHOR
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Relative differences in the positions of the stars in the UVIT imagesof the SMC taken with FUV-F154W and NUV-N263M are shown as vectorswhere the tail of the vector corresponds to the position in the NUV fieldPositions and errors are shown in subpixels For radii lt1900 subpixels anysource giving an error gt2 subpixels is either a close double or is at a radiusgt1900 subpixels in the FUV detector
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Relative positions FUV and NUV
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
PSF obtained
Each pixel ~ 041rdquo
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5
Typical flat field correction(Left FUV Right NUV)
rms variation lt 5