Creating a Median Dark

Once a set of dark images are obtained, the next task is to create a median dark image from the frames. This is accomplished by the perl script makedark. Running makedark is easy:

$ cd directory_with_darks                    ; Usually /rotse/data/3a1/

$ makedark

        This script will median all the darks of similar

        type located in the directory given as the argument.  A

        specific type can be specified if desired.

        Usage: makedark -d darkdir [-t datestr]

$ makedark -d .

makedark thens scan through the directory specified (usually the current directory), groups the dark frames by temperature and exposure length, takes the median of the dark images to create a dark with the filename of the form: YYMMDD_drk0200_3a.fit. (See Appendix A) The number after ``drk'' is the exposure time multiplied by 10.

It is worth the time to take a look at the median darks with ds9 to check for any light leak problems, read noise problems, or other systematics. Only good darks should be used in the automated pipeline.