Some problem with OmegaCam@VST calibration

[oleg]

Hello,
many OmegaCam@VST calibrated frames has one problem: some chips are more dark.
Look at my attached picture: chip #31 (top right corner) is more dark.

Any ideas?

[oleg]

Also, see calibrated frame with sky subtraction (Subtract a constant sky) from filter NB_659 (or Ha):

[mischa]

Hi Oleg,

your screenshots (or whatever you are uploading) do not make it into the forum (and they didn't appear attached to the email you sent yesterday, either). Maybe a file size issue?

[oleg]

Also, see calibrated frame with sky subtraction (Subtract a constant sky) from filter NB_659 (or Ha):

[mischa]

well, since we don't see the images: can you check whether that chip is already darker after the first calibration step ("calibrate data")? If so, how does the flat of that chip compare to that of the other chips? maybe it's saturated.

mischa

[oleg]

Hmm... Do you see this image?

[oleg]

Uncalibrated frame:

[oleg]

Chip #31 is already darker on original (raw) uncalibrated frames.