The Stratospheric Observatory for Infrared Astronomy (SOFIA) has significant recent scientific accomplishments including water on the moon and magnetic fields in molecular clouds. An airborne platform offers access to the sky at wavelengths where the atmosphere is opaque from the ground. It also has unique challenges that have been met with ingenious engineering solutions. I'll give an up to date report on the observatory at this conference.
The Stratospheric Observatory for Infrared Astronomy (SOFIA) is the world’s largest airborne observatory, featuring a
2.5 meter effective aperture telescope housed in the aft section of a Boeing 747SP aircraft. SOFIA’s current instrument
suite includes: FORCAST (Faint Object InfraRed CAmera for the SOFIA Telescope), a 5-40 μm dual band
imager/grism spectrometer developed at Cornell University; HIPO (High-speed Imaging Photometer for Occultations), a
0.3-1.1μm imager built by Lowell Observatory; GREAT (German Receiver for Astronomy at Terahertz Frequencies), a
multichannel heterodyne spectrometer from 60-240 μm, developed by a consortium led by the Max Planck Institute for
Radio Astronomy; FLITECAM (First Light Infrared Test Experiment CAMera), a 1-5 μm wide-field imager/grism
spectrometer developed at UCLA; FIFI-LS (Far-Infrared Field-Imaging Line Spectrometer), a 42-200 μm IFU grating
spectrograph completed by University Stuttgart; and EXES (Echelon-Cross-Echelle Spectrograph), a 5-28 μm highresolution
spectrometer designed at the University of Texas and being completed by UC Davis and NASA Ames
Research Center. HAWC+ (High-resolution Airborne Wideband Camera) is a 50-240 μm imager that was originally
developed at the University of Chicago as a first-generation instrument (HAWC), and is being upgraded at JPL to add
polarimetry and new detectors developed at Goddard Space Flight Center (GSFC). SOFIA will continually update its
instrument suite with new instrumentation, technology demonstration experiments and upgrades to the existing
instrument suite. This paper details the current instrument capabilities and status, as well as the plans for future
instrumentation.
SOFIA is a joint project between NASA and DLR, the German Aerospace Center, to provide the worldwide astronomical community with an observatory that offers unique capabilities from visible to far-infrared wavelengths. SOFIA consists of a 2.7-m telescope mounted in a highly modified Boeing 747-SP aircraft, a suite of instruments, and the scientific and operational infrastructure to support the observing program. This paper describes the current status of the observatory and details the General Investigator program. The observatory has recently completed major development activities, and it has transitioned into full operational status. Under the General Investigator program, astronomers submit proposals that are peer reviewed for observation on the facility. We describe the results from the first two cycles of the General Investigator program. We also describe some of the new observational capabilities that will be available for Cycle 3, which will begin in 2015.
The Stratospheric Observatory for Infrared Astronomy (SOFIA) is an airborne observatory, carrying a 2.5 m telescope onboard a heavily modified Boeing 747SP aircraft. SOFIA is optimized for operation at infrared wavelengths, much of which is obscured for ground-based observatories by atmospheric water vapor. The SOFIA science instrument complement consists of seven instruments: FORCAST (Faint Object InfraRed CAmera for the SOFIA Telescope), GREAT (German Receiver for Astronomy at Terahertz Frequencies), HIPO (High-speed Imaging Photometer for Occultations), FLITECAM (First Light Infrared Test Experiment CAMera), FIFI-LS (Far-Infrared Field-Imaging Line Spectrometer), EXES (Echelon-Cross-Echelle Spectrograph), and HAWC (High-resolution Airborne Wideband Camera). FORCAST is a 5–40 μm imager with grism spectroscopy, developed at Cornell University. GREAT is a heterodyne spectrometer providing high-resolution spectroscopy in several bands from 60–240 μm, developed at the Max Planck Institute for Radio Astronomy. HIPO is a 0.3–1.1 μm imager, developed at Lowell Observatory. FLITECAM is a 1–5 μm wide-field imager with grism spectroscopy, developed at UCLA. FIFI-LS is a 42–210 μm integral field imaging grating spectrometer, developed at the University of Stuttgart. EXES is a 5–28 μm high-resolution spectrograph, developed at UC Davis and NASA ARC. HAWC is a 50–240 μm imager, developed at the University of Chicago, and undergoing an upgrade at JPL to add polarimetry capability and substantially larger GSFC detectors. We describe the capabilities, performance, and status of each instrument, highlighting science results obtained using FORCAST, GREAT, and HIPO during SOFIA Early Science observations conducted in 2011.
The dominant non-instrumental background source for space-based infrared observatories is the zodiacal light
(ZL). We present Spitzer Infrared Array Camera (IRAC) measurements of the ZL at 3.6, 4.5, 5.8, and 8.0 μm,
taken as part of the instrument calibrations. We measure the changing surface brightness levels in approximately
weekly IRAC observations near the north ecliptic pole over the period of roughly 8.5 years. This long time
baseline is crucial for measuring the annual sinusoidal variation in the signal levels due to the tilt of the dust disk
with respect to the ecliptic, which is the true signal of the ZL. This is compared to both Cosmic Background
Explorer Diffuse Infrared Background Experiment data and a ZL model based thereon. Our data show a few
percent discrepancy from the Kelsall et al.(1998)1 model including a potential warping of the interplanetary dust
disk and a previously detected overdensity in the dust cloud directly behind the Earth in its orbit. Accurate
knowledge of the ZL is important for both extragalactic and Galactic astronomy including measurements of the
cosmic infrared background, absolute measures of extended sources, and comparison to extrasolar interplanetary
dust models. IRAC data can be used to further inform and test future ZL models.
SOFIA, the Stratospheric Observatory for Infrared Astronomy, is an airborne observatory with a 2.7-m telescope that is
under development by NASA and the German Aerospace Center DLR. From late 2010 and through the end of 2011,
SOFIA conducted a series of science demonstration flights, Early Science, using FORCAST (the Faint Object InfraRed
Camera for the SOFIA Telescope), HIPO (the High-speed Imaging Photometer for Occultations), and GREAT (the
German REceiver for Astronomy at Terahertz frequencies). Flying at altitudes as high as 13.7 km (45,000 ft), SOFIA
operates above more than 99.8% of the water vapor in the Earth’s atmosphere, opening up most of the far-infrared and
sub-millimeter parts of the spectrum. During Early Science, 30 science missions were flown with results in solar system
astronomy, star formation, the interstellar medium, the Galactic Center, and extragalactic studies. Many of these
investigations were conducted by the first group of SOFIA General Investigators, demonstrating the operation of SOFIA
as a facility for the astronomical community. This paper presents some recent highlights from Early Science.
A new nonlinear diffusion filtering scheme based on a nonlinear diffusion equation with a variable scale parameter is developed to preserve faint point sources while smoothing images for segmentation purposes. Application of the proposed approach to simulated, as well as to real images obtained by the Spitzer Space Telescope and by the Chandra X-ray Observatory reduced the Gaussian and Poisson noise successfully, while preserving both point sources and diffuse structures.
The Infrared Array Camera (IRAC) is one of three focal plane instruments on board the Spitzer Space Telescope. IRAC is a four-channel camera that obtains simultaneous broad-band images at 3.6, 4.5, 5.8, and 8.0 μm in two nearly adjacent fields of view. We summarize here the in-flight scientific, technical, and operational performance of IRAC.
KEYWORDS: Calibration, Infrared telescopes, High dynamic range imaging, Space telescopes, Stray light, Infrared cameras, Stars, Infrared radiation, Space operations, Telescopes
We describe the astronomical observation template (AOT) for the Infrared Array Camera (IRAC) on the Spitzer Space Telescope (formerly SIRTF, hereafter Spitzer). Commissioning of the AOTs was carried out in the first three months of the Spitzer mission. Strategies for observing fixed and moving targets are described, along with the performance of the AOT in flight. We also outline the operation of the IRAC data reduction pipeline at the Spitzer Science Center (SSC) and describe residual effects in the data due to electronic and optical anomalies in the instrument.
The Infrared Array Camera (IRAC) on Spitzer Space Telescope includes four Raytheon Vision Systems focal plane arrays, two with InSb detectors, and two with Si:As detectors. A brief comparison of pre- flight laboratory results vs. in-flight performance is given, including quantum efficiency and noise, as well as a discussion of irregular effects, such as residual image performance, "first frame effect", "banding", "column pull-down" and multiplexer bleed. Anomalies not encountered in pre-flight testing, as well as post-flight laboratory tests on these anomalies at the University of Rochester and at NASA Ames using sister parts to the flight arrays, are emphasized.
The Infrared Array Camera (IRAC) is one of three focal plane instruments in the Space Infrared Telescope Facility (SIRTF). IRAC is a four-channel camera that obtains simultaneous images at 3.6, 4.5, 5.8, and 8 microns. Two adjacent 5.12x5.12 arcmin fields of view in the SIRTF focal plane are viewed by the four channels in pairs (3.6 and 5.8 microns; 4.5 and 8 microns). All four detector arrays in the camera are 256x256 pixels in size, with the two shorter wavelength channels using InSb and the two longer wavelength channels using Si:As IBC detectors. We describe here the results of the instrument functional and calibration tests completed at Ball Aerospace during the integration with the cryogenic telescope assembly, and provide updated estimates of the in-flight sensitivity and performance of IRAC in SIRTF.
The Infrared Array Camera (IRAC) is one of three focal plane instruments in the Space Infrared Telescope Facility (SIRTF). IRAC is a four-channel camera that obtains simultaneous images at 3.6, 4.5, 5.8, and 8 microns. Two adjacent 5.12 X 5.12 arcmin fields of view in the SIRTF focal plane are viewed by the four channels in pairs (3.6 and 5.8 microns; 4.5 and 8 microns). All four detectors arrays in the camera are 256 X 256 pixels in size, with the two shorter wavelength channels using InSb and the two longer wavelength channels using Si:As IBC detectors. We describe here the results of the instrument functionality and calibration tests completed at Goddard Space Flight Center, and provide estimates of the in-flight sensitivity and performance of IRAC in SIRTF.
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