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Knowledgebase: IRAC
What is the absolute and relative calibration accuracy in IRAC data?
Posted by Seppo Laine on 21 November 2008 12:14 PM

The absolute calibration accuracy for IRAC is discussed in Section 4.3 of the IRAC Instrument Handbook and is 3% for all channels in the cryogenic mission data, and currently 5% in the warm mission data. The repeatability is better than 1% for all channels. To obtain the stated absolute calibration accuracy, several effects need to be accounted for. If these effects are not taken into consideration, then the uncertainty in photometry can be 10% or more. Note that extremely high accuracy relative photometry (e.g., exoplanet observations) requires special observing techniques that are ill-suited to most other types of observing programs. Hence, while those programs can achieve relative photometric accuracy of better than a part in 1000, "typical" IRAC observations will not.