46.5 Cosmic Rays

Cosmic Ray Events by Threshold Level

Threshold	Count Rate of Cosmic Ray Events Above Threshold	Average Number per Event
9 DN	4.7 pixels/sec/CCD	2.7 pixels
20 DN	3.2 pixels/sec/CCD	1.88 pixels

The event rate is estimated at about 1.7 events per second per CCD. As expected, long observations are most affected by cosmic ray events. Generally any exposure longer than 10 minutes is split into multiple integrations unless it was specified otherwise by the observer. The STSDAS task crrej may be used to correct a series of images for cosmic rays.