SOFIA First Light: Observations with FORCAST
Terry Herter + FORCAST team
+ Project Team (Ames, Dryden, USRA)
TLH: 11-Jan-11
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Bottom Line
SOFIA works! FORCAST works! FORCAST images a 3.2x3.2 arcminute FoV with
0.75 arcsecond pixels from 5 – 37 m Obtained near diffraction limited performance
for > 30 microns
Flew 10 hour flights with ~ 3 hours at 43,000 feet and 6 hours at or above 41,000 feet See corresponding improvements in background
and transmission
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Outline
Preparation in pictures lab, hanger, lineops, characterization flights
Observatory performance Emissivity, PSF
Images FORCAST Science observations
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FORCAST in DAOF lab
From left: FORCAST w/ foreoptics (test equipment), counterweight rack, and PI rack
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FORCAST on the telescope
Positioning FORCAST to mount on telescope
Cryogen transfers on the plane
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Taking Flight
Preparation and flights consisted of the following: LineOps (Line Operations, 15 in total)
Park plane on tarmac and look at stars Allows end-to-end testing of H/W & S/W
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 and a number of calibrators
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Telescope mirror temperatures -30 to -40 C Primary-secondary emissivity ~ 7 %
Made by tipping FORCAST collimator off nominal
Pupil Images
centered tipped difference
Thermal Backgrounds
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4 6 8 10 12
-40
-30
-20
-10
0
10
utcstart
tem
pse
c1, t
emp
pri
1
Telescope Temperature vs. time
TA primary (red) and secondary (blue) temperatures vs. UT for short science flight #1
Primary mirror
Secondary mirror
10
0
-10
-20
-30
-40
Tem
pera
ture
(C
)
4 6 8 10 12Time (hr)
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10 0 -10 -20 -3050
60
70
80
temppri1
pe_
rate
Telescope Temperature vs. time
FORCAST/SOFIA background (photoelectron rate per pixel) at 37 m (with dichroic) for short science flight #2. Symbols indicate different zenith angles.
pe_r
ate
(Me-
/s/p
ix)
Primary Mirror Temperature (C)
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PSF comparisons
0 2 4 6 8 10
0
20
40
60
Distance (pixels)
Sig
nal
0 2 4 6 8 10
-15
-10
-5
0
5
10
Distance (pixels)
Sig
nal
Short term Long term
Scale same as short term
FWHM = 3.2 x 2.5Theta = 60 deg(2.4”x1.9”)
FWHM = 5.8 x 4.7Theta = 51 deg(4.4”x3.5”)
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10 20 304.0
4.5
5.0
5.5
6.0
Wavelength (microns)
FW
HM
Maj
or
Axi
s (p
ixel
s)
Image Quality
FWHM of PSF major axis vs wavelength from Short Science Flight #3 for two calibrators (red and blue symbols) at altitudes > 41k feet. The line shows the diffraction limit. Pixels are 0.75 arcseconds.
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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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Jupiter
Dark South Equatorial Belt (SEB) disappeared earlier this year, it is now reappearing. FORCAST Observed SEB Outbreak (SEB) at a variety of wavelengths including filters in the H2 absorption trough on 12-Dec-2010.
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Jupiter
Rough animation at 5.4 micron show rotation of Jupiter using observations from a single observing segment. The images are the same except with the scaling changed. Covering 35 minutes
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M42
Observed M42 1c and Orion bar regions
6.4 (PAH), 6.6, 7.7 (PAH), 11.3 (PAH), 19.7, 31.4, and 37.1 m
Science Objectives: Determine luminosities of sources in the BNKL
region Measure SED of Orion proplyds to look at disk
termination Very hard due to structure in nebular emission
Excitation and destruction of PAH through the bar (ionization/shock front)
SOFIA: Orion Image
Left: Visible (HST, O’Dell and Wong), Middle: Near-IR (McCaughrean), Right: SOFIA 19.7 m (green) + 37 m (red) image