sofia: first light to first science - cornell...
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First Light to First Science 1
SOFIA: First Light to First Science
FORCAST Team members: Terry Herter (Principal Investigator), Joe Adams (Project Scientist), George Gull (Lead Engineer), Justin Schoenwald (Software Engineer), Chuck Henderson (Mechanical Eng), Luke Keller (Ithaca College, Co-I)
Ryan Lau (Grad. Student); Jason Wang & Lea Hirsch (Undergrads); Gordon Stacey (Co-I), Thomas Nikola (Co-I)
Final Exam Reminder
Final Exam: Friday, Dec 7, 2:00 – 4:30 PM
BKL 200: Baker Lab 200
Make-up Final Tuesday, Dec 11, 7:00 – 9:30 PM
105 Space Sciences Building
You must have a valid reason to take the make-up
You must get prior permission and sign up before the end of classes (Friday, Nov 30)
Review Sessions – Malott 251 Monday, Dec. 3 from 6:30 – 8:30 pm
Tuesday, Dec. 4 from 6:30 – 8:30 pm
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Outline
The FORCAST Instrument
FORCAST Science
SOFIA and FORCAST Preparation and First light – truly a once in a
lifetime experience
First Light
Observatory Characterization
Science Images & Discussion
Summary
FORCAST Facility Instrument
Built at Cornell
Turn over to NASA this fall
Dual-Channel 256x256 Camera w/ Si BIB arrays 5-25 m with Si:As array (SWC)
25-40 m with Si:Sb array (LWC)
Selectable Filters in 5-40 m range
Field of View 0.75''/pixel giving a 3.2'3.2'
Designed for diffraction-limited imaging for > 15 µm
Able to observe with the SWC and LWC simultaneously But with some penalty in sensitivity in
the LWC
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FORCAST Filters
FORCAST filter transmissions (black) overlaid on atmospheric transmission from SOFIA (blue) and from Mauna Kea (red) Roughly 10 m vs. 1 mm precipitable water vapor
Except for very limited bands, transmission for ground based observatories is poor over the 5 – 40 m region
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FORCAST Detects “Dirt”
FORCAST is sensitive to emission from dust in the interstellar medium UV and optical photons heat the dust which radiates in the
“thermal” infrared
Dust composition, heating sources, geometry, and optical depth all affect the observed spectrum.
“Large” particles Emitted power in equilibrium with absorbed radiation
Have a well-defined temperature
“Small” particles Temperature significantly affected by single photon
Depends on heat capacity of grain
e.g. PAH’s (Polycyclic Aromatic Hydrocarbons)
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Orion: A Different ViewInfrared (IRAS)Visible Light
The IR affords a complementary view of the Universe relative to other wavelengths –The bright extended regions in IRAS view are due to thermal emission from small grains (dust) heated by stellar radiation. Complex molecules emit in the IR and
submillimeter regions of the spectrum
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rms ~ 0.49 DN
Nod Subtracted
Mid-infrared Data Acquisition
FORCAST data from OCF#3 on calibration star Alpha Cet at 37.1 micron. The integration time in a single image is 30 seconds. The features in the chop-subtracted image likely dominated by the dewar window but involve all of the optical system on either side of the secondary mirror.
Raw Image
rms ~ 350 DN
Chop-Subtracted
rms ~ 1.4 DN
The thermal emission from the atmosphere and warm optics (telescope, etc.) create a background which we must look through (generating photon noise)
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“Original” Team Science Objectives
The Galactic Center region Nature of circumnuclear ring (CNR)
Excitation of “arches”
Star formation Census of “protostars” in nearby molecular clouds
Spiral arms of nearby galaxies
Circumstellar disks Spatially resolve Vega phenomena
Spectral energy distribution of Young Stellar Objects
Start of FORCAST funding: 1997 !
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NASA Lear JetObservatory
1967
30-cm telescope
NASA Kuiper Airborne Observatory (KAO)
1974
91-cm telescopeNASA/DLR Stratospheric Observatory
for Infrared Astronomy (SOFIA)
2010
2.5-m telescope1975 until 1996 (shut down in
prep for SOFIA)Early 70’s until 1980.
Started operations in 2010
Evolution of Airborne Astronomy
Cornell has been a part of airborne astronomy since its inception (Martin Harwit & Jim Houck)
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SOFIA
Instrumentation: wide variety, rapidly interchangeable, state-of-the art – SOFIA is a new observatory every few years
Mobility: anywhere, anytime Deployments to the Southern Hemisphere
and elsewhere
Twenty year design lifetime >120 8-10 hour flights per year
Flight altitude 41,000 – 45,000 ft
Collaboration between NASA and DLR (Germany)
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The SOFIA Observatory
open cavity (door not shown)
2.5m telescope
pressure bulkhead
scientific instrument
scientist stations, telescope and instrument control, etc.
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Telescope and aperture assembly
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Primary Mirror Installed Oct. 8, 2008
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FORCAST in the Lab
Extensive testing done in the lab Flight data acquisition simulations
Run two arrays at different rates while synching to a chopping secondary
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FORCAST in DAOF lab
From left: FORCAST w/ foreoptics (test equipment), counterweight rack, and PI rack
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Installation on the plane
Installing PI rack & getting FORCAST into the plane
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Attaching FORCAST
George and Charlie positioning FORCAST
George and Chuck fastening FORCAST to telescope
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Cryogen transfers on the plane
George and Luke in their LN2 transfer “costumes”
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Example Flight: Galactic Center
Early science flight limited to within 200 miles of NASA Dryden
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Flight Log ….Preparation and flights consisted of the following:
LineOps (Line Operations, 19 in total) Park plane on tarmac and look at stars
Allowed end-to-end testing of H/W & S/W
This provided extremely important practice
Observatory characterization flights 25-May-2010, 10-Nov-2010, 18-Nov-2010
Observatory operational and performance checkout
High speed “jitter” measurements of bright stars
Also measured primary-secondary telescope emissivity
Short Science flights 30-Nov-2010, 03-Dec-2010, 07-Dec-2010
Observed Jupiter, Comet Hartley 2, M42, W3, M82 + calibrators
Basic Science flights (support of guest investigations) 10 flights: 05-May through 07-Jun-2011
On the Tarmac for LineOps
Left: Setting up the plane for a “LineOp”(line operation)
Right: Door open, looking at an alignment and calibration star
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Preflight Safety Briefing
I don’t think Ryan believes him
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TACFL: In flight operations
Holgar, Randy, Andy, and Uli at work
Jim and Joe (foreground),
Alan (background)
TACFL (Telescope Assembly Characterization and First Light) = OCF#1 (Observatory Characterization Flight #1)
First photons ever collected on a SOFIA flight! (May 25, 2010)
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It’s the plane that’s moving
Apparent motion of telescope as plane pitches, rolls, and yaws.
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TACFL: First “Science” Integration
M82 – first chop-nod sequence: 24 m (left) and 37 m (right)
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Example Flight Plan
Sgr A
Ceph
Boo
Lyr
Sgr A
Ceph
Flights are 10 hours long but typically go by very quickly!
NASA Test Pilotquizzing me
Hans Zinneckerquizzing me
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FORCAST Science Observations
Sample Science Images Jupiter
Orion and W3 star forming regions
Pistol/Sickle region of Galactic Center Most luminous star in the galaxy?
Circumnuclear disk around Sgr A* Feeding the monster?
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Jupiter
Multi-wavelength imaging of Jupiter with FORCAST
Peter Gierasch along with Barney Conrath and Jason Wang (CU undergrad) are analyzing and modeling the data (to look at H2 ortho to para ratio, etc.)
“Raw” 11.1 m Jupiter images – right image has been rescaled to show Callisto and Io (and noise level)
11.1 m
5.4 11.1 19.7 24.2 31.5 37.1
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Orion Nebula
Orion Nebula at the Sword of Orion is the closest region to the earth of Massive Star Formation Distance = 415 pc
Both Optical stars (Trapezium), embedded star formation (OMC 1/BNKL and OMC2)
Observed at 6.4 (PAH), 6.6, 7.7 (PAH), 11.3 (PAH), 19.7, 31.4, and 37.1 m
Science Objectives: Determine luminosity and spectral energy distribution (SED)
of sources in the BNKL region (De Buizer et al. 2012, ApJL)
Measure SED of Orion proplyds to look at disk termination (Shuping et al. 2012, ApJL)
SED and properties of OMC2 embedded stars with disks (Adams et al. 2012,ApJL)
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SOFIA: Orion Image
Left: Visible (HST, O’Dell and Wong),
Middle: Near-IR (McCaughrean),
Right: SOFIA 19.7 m (green) + 37 m (red) image
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KAO 38 um
(Stacey et al. 1995)
BN/KL RegionBlue=19um Green=31um Red=37um
De Buizer et al. (2012)
SOFIA
Background Image:Spitzer
BN
IRc3
IRc4
IRc2
Source I
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W3: from previous to the present
Above left: Spitzer composite image at 3.6, 4.5, and 8.0 m of W3 (Ruch et al. 2007). Middle: 20 m image from Wynn-Williams, et al. 1972 and FIR images from Werner et al. 1980. Right: Images from SOFIA
20 m (Mt Wilson)
30 m (KAO)
50 m (KAO)
19.7 m
31.5 m
37.1 m
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GC Science
Pistol Nebula & Quintuplet Cluster Pistol star may be the most luminous star in our galaxy (Teff
~ 14,000 K) Nebula is a result of mass loss from the star
Ryan Lau working on paper discussing morphology and dynamics of the nebula What is source of heating of the dust?
What are the dynamics of the stellar winds in the region?
Circumnuclear ring Almost perfect r ~ 1.5pc ring around the 4x106 Msun BH
Thickness/Diameter ~ only 1/10; inclination to galaxy ~18°
Clear color gradient seen across the ring: internally heated
Probably by young stars interior to the ring
Interesting structure on fine scales
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The Galactic Center
At right are mulitcolor infrared images of two regions of the center of the Milky Way made from SOFIA.
SOFIA/FORCAST images at 19.7 (blue), 31.5 (green), 37.1 (red) m
Radio image of Sgr A, pistol, sickle, filaments and arches
120 lightyears
Sgr A - CND
Mulitcolor image of circumnuclear disk (CND) in the Galactic Center.
Scaling varies from left (scaled to central brightness) to right(scaled to emphasize ring)
19.7 (blue), 31.5 (green), 37.1 (red)
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Experiences flying on SOFIA
It has been both challenging and rewarding We are part of a making a highly complex system
work
But, of course, that is the point (to push new boundaries)
At every stage things have worked better than (I personally) expected
Observatory performance is quite good Would like continued image quality improvement
Great team effort by everyone
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Summary
Science flights have been highly successful. 3 Short Science and 10 Basic Science have lots of
publishable results
Science breadth Wide range of programs covering planetary
science, star formation, stellar evolution, the interstellar medium, and others.
FORCAST niche will be Spatial resolution & wavelength coverage
(Grism) spectroscopy (to be commissioned the next time FORCAST flies)
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What should you remember?
Interstellar dust Emits primarily in the infrared (IR)
“Thermal” IR wavelengths: ~ 2 m to ~ 200 m
Atmospheric transmission Generally poor in the infrared
Must get above (most of) the atmosphere to look at the sky
Infrared emission Important for studying star forming regions
Can see through dust to see newly born stars
Questions?