The Infrared Array Camera (IRAC) is now the only science instrument in operation on the Spitzer Space Telescope. The
3.6 and 4.5 µm channels are temperature-stabilized at ~28.7K, and the sensitivity of IRAC is nearly identical to what it
was in the cryogenic mission. The instrument point response function (PRF) is a set of values from which one can
determine the point spread function (PSF) for a source at any position in the field, and is dependent on the optical
characteristics of the telescope and instrument as well as the detector sampling and pixel response. These data are
necessary when performing PSF-fitting photometry of sources, for deconvolving an IRAC image, subtracting out a
bright source in a field, or for estimating the flux of a source that saturates the detector. Since the telescope and
instrument are operating at a higher temperature in the post-cryogenic mission, we re-derive the PRFs for IRAC from
measurements obtained after the warm mission temperature set point and detector biases were finalized and compare
them to the 3.6 and 4.5 µm PRFs determined during the cryogenic mission to assess any changes.
We present an overview of the calibration and properties of data from the IRAC instrument aboard the Spitzer Space
Telescope taken after the depletion of cryogen. The cryogen depleted on 15 May 2009, and shortly afterward a two-month-
long calibration and characterization campaign was conducted. The array temperature and bias setpoints were
revised on 19 September 2009 to take advantage of lower than expected power dissipation by the instrument and to
improve sensitivity. The final operating temperature of the arrays is 28.7 K, the applied bias across each detector is 500
mV and the equilibrium temperature of the instrument chamber is 27.55 K. The final sensitivities are essentially the
same as the cryogenic mission with the 3.6 μm array being slightly less sensitive (10%) and the 4.5 μm array within 5%
of the cryogenic sensitivity. The current absolute photometric uncertainties are 4% at 3.6 and 4.5 μm, and better than
milli-mag photometry is achievable for long-stare photometric observations. With continued analysis, we expect the
absolute calibration to improve to the cryogenic value of 3%. Warm IRAC operations fully support all science that was
conducted in the cryogenic mission and all currently planned warm science projects (including Exploration Science
programs). We expect that IRAC will continue to make ground-breaking discoveries in star formation, the nature of the
early universe, and in our understanding of the properties of exoplanets.
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.
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) 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.
IRAC, the Infrared Array Camera on the Spitzer Space Telescope, generated well over 150,000 images during the in-orbit checkout and science verification phase of the mission. All of these were processed with SIP, the SAO IRAC Pipeline. SIP was created by and for the members of the IRAC instrument team at the Smithsonian Astrophysical Observatory, to allow short-timescale data processing and rapid-turnaround software testing and algorithm modification. SIP makes use of perl scripting and data mirroring to transfer and manage data, a mySQL database to select calibration data, and Python/numarray to process the image data; it is designed to run with no user interaction. SIP is fast, flexible, and robust. We present some 'lessons learned' from the construction and maintenance of SIP, and discuss prospects for future improvement.
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 major scientific instruments to be launched aboard the Space Infrared Telescope Facility (SIRTF). This document briefly describes the features, usage, and limitations of the IRAC Science Data Simulator (ISDS) that can be used to generate simulated data to anticipate data quality and reduction issues for mission operations. The software is a combination of C++ and IRAF SPP routines that implement the features already characterized during the integration and test phase of IRAC's
development. While no guarantee of accuracy is made, the intention is to replicate as faithfully as possible known characteristics and artifacts of the IRAC instrument. The many beneficial applications of the ISDS include facilitating planning of the IRAC pipeline by the SIRTF Science Center (SSC), and validating observing strategies for SIRTF Guaranteed Time Observers and Legacy teams. The simulator has already been used by mission planners to demonstrate the relative effectiveness of different approaches to data reduction. It will also be of great value in demonstrating IRAC's capabilities for mapping and source detection, and in testing post-pipeline software currently being developed for these purposes.
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.
The Space IR Telescope Facility (SIRTF) contains three focal plane instruments, one of which is the IR Array Camera (IRAC). IRAC is a four-channel camera that provides simultaneous 5.12 X 5.12 arcmin images at 3.6, 4.5, 5.8 and 8 microns. The pixel size is 1.2 arcsec in all bands. Two adjacent fields of view in the SIRTF focal plane are viewed by the four channels in pairs. All four detector arrays in the camera are 256 by 256 pixels in size, with the two short wavelength channels using InSb and the two longer wavelength channels using Si:As IBS detectors. The IRAC sensitivities at 3.6, 4.5, 5.8, and 8.0 microns are 6, 7, 36, and 54 microJanskys, respectively. Two of the most important scientific objectives of IRAC will be to carry out surveys to study galaxy formation and evolution during the early stage of the Universe, and to search for brown dwarfs and superplanets.