| Telescope | MDM 1.3m |
| Date | 11/23/98 |
| Instrument | Echelle CCD |
| Filter | V |
| Exposure Time |
750 sec |
Problem:In this image, a large number of cosmic rays can be seen (several in this small portion of the image are circled in green). These omnipresent streaks and dots in the image are caused by cosmic rays (high energy particles) striking the CCD. The ones that look like streaks are easy to identify and disregard. The pointlike ones are slightly less obvious, but can be distinguished from stars by their radial profile which is pointlike rather than gaussian (the shape of the stellar profile). |
Fix:Reducing your exposure time will reduce the number of cosmic rays in your image but there is nothing you can do to entirely avoid cosmic rays. However, if you take multiple exposures of the same field, median combining them together will remove the cosmic rays from the final image. |