5/21/2015g.c.stewart berlin 1 astrosat: a multi-wavelength satellite 1st dedicated indian...

04/18/23G.C.Stewart Berlin 1

ASTROSAT: A Multi-Wavelength Satellite1st Dedicated Indian Astronomical Mission

ISRO Satellite Centre (ISAC), Bangalore

Tata Institute of Fundamental Research, Mumbai

University of Leicester

Indian Institute of Astrophysics (IIA), Bangalore

Inter-University Centre for Astronomy & Astrophysics (IUCAA), Pune.

Canadian Space Agency

Raman Research Institute, Bangalore

Vikram Sarabhai Space Centre, Trivandrum

X-RAY

UV/Opt


ASTROSAT (1.55 tons 600 kms, nearly equatorial orbit by PSLV, 3

gyros and 2 star trackers for attitude control by reaction wheel system with a Magnetic torquer )

Soft X-ray Telescope

3 Large Area Xenon Proportional Counters

2 UV(+Opt ) Imaging Telescopes

CZTI

Folded Solar panels

Radiator PlatesFor SXT and CZT

Scanning Sky Monitor (SSM)


UVIT: Two Telescopes f/12 RC Optics Focal Length: 4756mm Diameter: 38 cm Simultaneous Wide

Angle ( ~ 28’) images in FUV (130-180 nm) in one and NUV (180-300 nm) & VIS (320-530 nm) in the other

MCP based intensified CMOS detectors

Spatial Resolution : 1.8” Sensitivity in FUV: mag.

20 in 1000 s Temporal Resolution ~

30 ms, full frame ( < 5 ms, small window )

Gratings for Slit-less spectroscopy in FUV & NUV

R ~ 100


UVIT: filters


GALEX UVITFoV (Circular dia) 1.24 degrees 27 arc-min

No. of bands 2 (NUV, FUV) 2 channels (NUV, FUV) + Vis

Filters in NUV NIL 5 filters

Filters in FUV NIL 5 filters [multiple colour-colour diagrams]

Spectroscopy Grism Grating

Resolution R ~ 100-120 R ~ 100

No. of grism/grating 1 per band 2 per band

Angular resolution 4.5-6.0 arcsec 1.8 arc-sec (FWHM)

Saturation < 10 mag < 8.0 mag (neutral density filter)

[can image fields with bright objects]

Time resolution ~ 10 milli-sec ~ 5.0 milli-sec (window mode)

~ 30 milli-sec full field

Energy Range : 3-80 keV

(50 Mylar window, 2 atm. of 90 % Xenon + 10 % Methane)

Effective Area : 6000 cm² (@ 20 keV)

Energy Resolution : ~10% FWHM at 22 keV

Field of View : 1° x 1° FWHM

(Collimator : 50µ Sn + 25µ Cu + 100µ Al )Blocking shield on sides and bottom : 1mm Sn + 0.2 mm Cu

Timing Accuracy: 10 μsec in time tagged mode

(oven-controlled oscillator).

Onboard purifier for the xenon gas

Large Area Xenon Proportional Counter (LAXPC): Characteristics



LAXPC: Effective Area

Large Area X-ray Proportional Counter (LAXPC)



LAXPC: Collimator

CZT Imager characteristicsArea 1024 cm 2

Pixels 16384

Pixel size 2.4 mm X 2.4 mm (5 mm thick)

Read-out ASIC based (128 chips of 128 channels)

Imaging method Coded Aperture Mask (CAM)

Field of View 17 X 17 deg2 (uncollimated)

6 X 6 (10 – 100 keV) – CAM

Angular resolution 8 arcmin

Energy resolution 5% @ 100 keV

Energy range 10 – 100 keV - Up to 1 MeV (Photometric)

Sensitivity 0.5 mCrab (5 sigma; 10 4 s)


CZT-Imager with a coded mask

(Qualification Model)


CZT Detector 4 cm X 4 cm

CZT crystal

Connectors HV Connector

Thermalconductor

Thermalconductor

ASIC



SXT CharacteristicsTelescope Length: 2465 mm (Telescope + camera + baffle + door)

Top Envelope Diameter: 386 mm Focal Length: 2000 mmEpoxy Replicated Gold Mirrors on Al substrates in conical Approximation to Wolter I geometry.Radius of mirrors: 65 - 130 mm; Reflector Length: 100 mmReflector thickness: 0.2 mm (Al) + Epoxy (~50 microns) + gold (1400 Angstroms)

Minimum reflector spacing: 0.5 mmNo. of reflectors: 320 (40 per quadrant) Detector (Swift Heritage): E2V CCD-22 600 x 600

Field of view : 41.3 x 41.3 arcmin

PSF: 3 – 4 arcminsSensitivity (expected): few x 10-14 cgs (1 cps/mCrab)


Soft X-ray Telescope

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•Four Fe-55 calibration (corner) sources•One Fe 55 calibration door source•Optical Blocking Filter•CCD Assy. including TEC•PCB with front-end electronics

G.C.Stewart Berlin


SXT Engineering and Flight Models

Astrosat SXT FM FPCA in Thermal Vacuum Chamber at Birmingham

University



CCD Performance Nominal•Noise ~6 – 10 e-

•Resolution at Mn ~157 eV (Lab Electronics)

SXT CCD (Eng.) Data with TIFR built Electronics

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5.9 and 6.4 keV peaks

Si escape peaks3.70 and 4.15 keV

Isolated pixels only

Resolution ~140 eV

G.C.Stewart Berlin

Door and Corner X-ray Calibration Sources

Optical LED Image


SXT Effective Area vs. Energy (after subtraction of shadowing effects due to holding structure)

04/18/23 24G.C.Stewart Berlin

Scanning Sky Monitor (SSM) Detector : 3 x Proportional counters

with resistive anodes Ratio of signals on either ends of anode

gives position. Energy Range : 2 - 10 keV Position resolution : 1.5 mm Field of View : 10o x 90o (FWHM) Sensitivity : 30 mCrab (5 min

integration) Time resolution : 1 ms Angular resolution : ~ 10 arc min



Status Engineering Environmental Tests almost

complete Flight Model Construction Well Advanced

(UVIT detectors and SXT CCD camera complete)

Spacecraft Assembly begun – most subsystems complete

Launcher Assigned Launch Date

ASTROSAT – Key Strengths

Simultaneous V/UV to hard X-ray measurements

LEO+ 70 inclinclination Low , stable? Background

Large area at high X-ray energies UV imaging capability Low pile-up in CCD Fast Slewing ??


ASTROSAT – Key Projects1. AGN/Binaries: Simultaneous UV to hard X-

ray timing/monitoring2. Galactic Novae: UV to X-ray Observations

(TOO program)3. Magnetars: Multi-wave observations4. LMXBs: Persistent Pulsations and

thermonuclear bursts5. Galactic Black Holes and micro / nano

quasars6. Binary X-ray Pulsars: Cyclotron Resonance

Scattering Features (X-ray Observations)7. Clusters of galaxies: X-ray & UV

Observations


ASTROSAT – Key Projects

10. Supernova Remnants: X-ray and UV Observations

11. UVIT observations ofa) Star Forming galaxies, b) Young stellar objects, c) Galactic Structure, d) Proto- and Planetary Nebulaee) UV Extinction in the Galaxy (Archival Data)

12. Miscellaneous: a) Study nano quasars and Compton thick sources, b) Observations of Stellar Flares, c) GLAST/INTEGRAL/BAT Sources, d) Surveys - multi wave, deep fields


AGN (bright)

• 4/5 decade SEDs - Resolving all the spectral components : UV and soft X-rays (thermal) from accretion disk, hard X-ray reflection component, intrinsic power-law component

• Variability correlation and lags between UV, soft and hard X-rays

• Variability correlation and lags between Fe-K line and Compton Reflection

•Bright Compton thick 04/18/23G.C.Stewart Berlin 32


SXT: Clusters of galaxies

C

SXT

LAXPC

CZTI

H

Spectral model from Rephaeli et al. (1999)

Binary X-ray Pulsars with AstrosatSimulated 10 ks observations of hard X-ray spectrum of Accreting Pulsar 4U

0115+63 The cyclotron lines are well resolved by ASTROSAT



PV Phase(6 months)

Guaranteed Time(6 months

2nd Year 3rd Year 3+? Yr

X-ray Teams

67% 67% 32.5% 20% _

UVIT Team 33% 33% 17.5% 10% _

Indian Proposals

_ _ 35% 45% 65%

International Proposals

_ _ _ 10% 20%

Canada _ _ 5% 5% 5%

Leicester _ _ 3% 3% 3%

TOO _ _ 5% 5% 5%

Calibration _ _ 2% 2% 2%

Time Allocation


Coming Next Year !

Simultaneous UV to hard X-ray spectral measurements with ASTROSAT: Blazars,

HPQs, OVVs etc.Science Drivers: Jet Physics, particle injection and

acceleration• Synchrotron X-ray emission from the highest energy e-• Electron/proton injection. • Acceleration and cooling related variability patterns in Sync. components of FSRQs and LBLs. • UV and soft X-ray variability can pin down the transition between the emission from slow and fast cooling e- and thus obtain estimates of magnetic field and Doppler factors of the jets.• Shocks in jets. Geom: viewing angle, jet opening angle.• Underlying Accretion disk in Blazars ? Can be revealed during minima when the beamed component is suppressed.


5/21/2015g.c.stewart berlin 1 astrosat: a multi-wavelength satellite 1st dedicated indian...

Documents

stewart berlin

field slide

collimator slide

effective area slide

kev energy resolution

filters filters

trivandrum xray uvopt

fuv nuv r