This paragraph shows the very simplest possible example of how to do the relative calibration of a CCD-frame. It is assumed that frames are only taken in a single filter (R in this case). The frames available are the following:
AVERage/IMAge DARKAV = DARK01,DARK02,DARK03,DARK04The first two commands compute the simple averages of the dark and flat field images. The third command computes the dark subtracted average flat field. The final two commands perform the flat fielding of the data frames. Note that there has been no correction for bad columns in either the flat field, the dark frames or the data frames. The next example shows how to do this.
AVERage/IMAge FLATAV = FLATR1,FLATR2,FLATR3
COMPute/IMAge DENOM = FLATAV-DARKAV
COMPute/IMAge N5126RF = (N5126R-DARKAV)/DENOM
COMPute/IMAge N7794RF = (N7794R-DARKAV)/DENOM