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I have an observation with frame repeats, and the repeated frames are full of weird (usually column-wise) structure. What can Ido to fix these data?
Posted by Seppo Laine on 15 March 2010 05:08 PM

The first frame correction in the pipeline has not worked well for such data. This was sometimes true for channel 3 data in the cryogenic mission and this is currently always true for warm IRAC data. The first-order mitigation is fairly simple. Take a median average with outlier rejection of the difference images between the first repeat and a given repeat, for example, median-average the difference between the first and the second repeat frames (and similarly, but separately, median-average the difference between the first and the third repeat frames, etc.) Then add these median difference images to your individual (C)BCD frames. For example, you would add the median difference of the first and second repeat frames to each second repeat frame.

An IDL code to perform this "delta-dark" correction is available in the Spitzer Contributed software section at

https://irsa.ipac.caltech.edu/data/SPITZER/docs/dataanalysistools/tools/contributed/irac/repeatdeltadark/
.