crcombine -- combine multiple exposures to eliminate cosmic rays
crcombine input output
See parameters for imcombine .
This task is a version of imcombine . See the help for that task for a description of the parameters and algorithms.
For the purpose of removing cosmic rays the most useful options are the "crreject" algorithm and/or combining with a median. Many other options may work as well. The best use of this task depends on the number of images available. If there are more than a few images the images should be combined with an "average" and using a rejection algorithm.
1. To combine two images using the gain and read noise parameters in the image header:
cl> crcombine obj012,obj013 abc gain=gain rdnoise=rdnoise