Problem: The image is saturated

If the image is completely saturated, or fails basic quality cuts (e.g., the minimum value in the central subframe is above some cut-off, usually 30000), the system will only write the fits header to disk. In the logfile on the camera computer you will see a message similar to:

Aug 21 01:07:16 cam3a camserverd: image screwed up, not writing it: 0

When you look at the image with ls, you will see:

-rw-rw-r- 1 observer observer 8640 Aug 21 08:30 020817_sky1409+0148_3a001_c.fit

Reading the fits header will make the problem obvious: for this image, the mean in the central subframe was 33035, very close to saturation.

The solution to this problem is simple: take a shorter exposure, or wait for clear weather!