IRAC Instrument Handbook - IRSA - California Institute of Technology

Table of Contents
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IRAC Instrument Handbook
1 Introduction ..............................................................................................................................1
1.1 DOCUMENT PURPOSE AND SCOPE .............................................................................................................................. 1
1.2 BA SIC DEFINITIONS ...................................................................................................................................................... 1
1.3 IRA C ESSENT IALS ........................................................................................................................................................ 2
1.4 STANDARD ACKNOWLEDGMENT S FOR IRAC PUBLICATIONS................................................................................ 2
1.5 HOW TO CONTACT US .................................................................................................................................................. 3
2 Instrument Description..............................................................................................................4
2.1 OVERVIEW ..................................................................................................................................................................... 4
2.2 DESCRIPT ION OF OPTICS .............................................................................................................................................. 5
2.2.1 Field of View (FOV)................................................................................................................................................ 5
2.2.2 IRAC Image Quality................................................................................................................................................ 6
2.2.3 Spectral Response.................................................................................................................................................... 8
2.2.4 Distortion ................................................................................................................................................................ 10
2.3 DETECTORS.................................................................................................................................................................. 11
2.3.1 Design...................................................................................................................................................................... 11
2.3.2 Performance ........................................................................................................................................................... 11
2.4 ELECT RONICS .............................................................................................................................................................. 13
2.4.1 Hardware ................................................................................................................................................................ 13
2.4.2 Fowler Sampling.................................................................................................................................................... 13
2.4.3 Exposure Times and Frame Time ....................................................................................................................... 14
2.4.4 Subarray Mode....................................................................................................................................................... 15
2.4.5 Calibration Lamps................................................................................................................................................. 15
2.4.6 Firmware................................................................................................................................................................. 15
2.5 SENSITIVIT Y AND SAT URATION ................................................................................................................................ 16
2.5.1 Sensitivity ................................................................................................................................................................ 16
2.5.2 Saturation................................................................................................................................................................ 24
3 Ope rating Modes .....................................................................................................................26
3.1 READOUT MODES AND FRAME TIMES DURING CRYOGENIC OPERATIONS........................................................ 26
3.2 MAP GRID DEFINITION............................................................................................................................................... 27
3.3 DITHERING PATTERNS................................................................................................................................................ 27
4 Calibration ..............................................................................................................................31
4.1 DARKS .......................................................................................................................................................................... 31
4.2 FLAT FIELDS ................................................................................................................................................................ 32
4.3 PHOTOMETRIC CALIBRATION.................................................................................................................................... 34
4.4 COLOR CORRECTION .................................................................................................................................................. 37
4.5 ARRAY LOCATION-DEPENDENT PHOTOMETRIC CORRECTIONS FOR COMPACT SOURCES WITH STELLAR
SP ECT RAL SLOPES ..................................................................................................................................................................... 42
4.6 PIXEL PHASE-DEPENDENT PHOT OMETRIC CORRECTION FOR POINT SOURCES................................................. 45
4.7 IRA C POINT SPREAD AND POINT RESP ONSE FUNCTIONS .................................................................................... 46
4.7.1 Core PRFs .............................................................................................................................................................. 48
4.7.2 Extended PRFs....................................................................................................................................................... 49
4.7.3 Point Source Fitting Photometry ........................................................................................................................ 50