Automatic Removal of Cosmic Ray Signatures on Deep Impact CCDs
  The results of recognition of cosmic ray (CR) signatures on a single image were analyzed for several codes written by several authors. For most visual images made during low solar activity at exposure time t>4 s, the number of clusters of bright pixels on an image per second per sq. cm of CCD was about 2-4, both for dark and normal sky images. At high solar activity, it sometimes exceeded 10. The ratio of the number of CR signatures consisting of 'n' pixels obtained at high solar activity to that at low solar activity was greater for greater 'n'. The number of clusters detected as CR signatures on a single infrared image is by at least a factor of several greater than the actual number of CR signatures; the number of clusters based on analysis of two successive dark frames is in agreement with an expected number of CR signatures. Some glitches of false CR signatures include bright pixels presented on different infrared images. Our interactive code allows one to delete long CR signatures and prevents removal of false CR signatures near the edge of a comet. 
S. I. Ipatov, M. F. A'Hearn, and K. P. Klaasen