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Knowledgebase: IRAC
Why, in the IRAC overlay in Spot, does it have two identical frames taken at my first observing position? OR, why do I have two BCD files for the first observing position?
Posted by Seppo Laine on 21 November 2008 11:47 AM
Every IRAC full array AOR with a frame time equal to or greater to 6 seconds will have its first frame taken in the high dynamic range (HDR) mode. Therefore, you will get one or two short frames before the long exposure at exactly the same position (see the Spitzer Observer's Manual for the frame times and number of frames taken in HDR mode). The first frame HDR mode observation is executed to help us to mitigate the first frame effect, also documented in Spitzer Observer's Manual. The subsequent frames will be taken with your selected frame time only.