The command COMBINE/CCD is used to combine several images. The command itself has a number of options to use DO tables or catalogues, but the simplest version takes the form:
COMBINE/CCD type images outputwhere type is one of BS (for bias), FF (for flat field), DK (for dark), SK (for sky) and OT (for other) and is used to indicate what type of image you are combining; images is a comma separated list of images you wish to combine; output is the name of the resulting output file. Scaling and/or shifting options can be specified for each of these image types. These parameters can be checked using SHOW/CCD type, and be set using SET/CCD type, where type, using the codes listed above, specifies the type of image whose combination parameters you are interested in. An example is displayed below:
COMBINE/CCD FF kflat1,kflat2,kflat3 kflatwill combine the images kflat1, kflat2 and kflat3 into an output image kflat using the combination options specified for the FF image type.