| Telescope | Las Campanas Obs. 1m |
| Date | 8/24/1997 |
| Instrument | SITe 1 |
| Filter | I |
| Exposure Time |
600 s |
| Other | Image unprocessed |
Problem:The saturated strip on the bottom of the image is due to a read out error. These usually happen in the electronics of the instrument, but they can occur due to a software error as well.Another feature visible on this image are the doughnuts due to out-of-focus dust grains on the dewar window which are a very common phenomenon. |
Fix:The best fix is to retake the image. If the problem reoccurs, the advice of the technical personnel responsible for the health of the telescope to the astronomer would (very likely) be not to touch anything and to call them for assistance.The dust doughnuts will go away when the image is processed with a flat field image. Larger doughnuts due to dust on the filters can potentially be a bigger problem as they may change position throughout the night due to the motion of the filter wheel. See link below to the other example of an image with dust rings for a more detailed explanation. |
Another example of a readout error
Back to first example of image with dust rings
Return to the "CCD Features" Directory