Check dome flats¶
Observers should examine at least one dome flat of each filter to make sure they have no obvious flaws. Correct dome flats will have
- Count levels roughly as follows. These are net counts, i.e. difference between array pixels and overscan pixels.
(*) note that the dome flat scripts take r-band exposures at two different exposure times to check linearity.
- All 62 science CCDs have read out properly
- All CCDs (except #61=N30) are uniform to a few percent
- No visible interference patterns or striping (a pattern of concentric rings is normal, as are bright strips along the CCD edges).