IRAC Instrument Handbook - IRSA - California Institute of Technology

Calibration 32 Flat Fields
IRAC Instrument Handbook
Figure 4.1: IRAC instrument dark current images. These measurements were made during a normal
campaign producing a skydark with an exposure time of 100 seconds.
4.2 Flat Fields
Pixel-to-pixel relative gain variations are commonly know as the "flatfield". To get the most accurate
measurement of the flatfield, including the effects of the telescope and the IRAC pickoff mirrors, one
must use observations of the sky. Because the IRAC detectors are relatively large, there are few discrete
astronomical objects large enough and bright enough to fill the detector field of view.