Two times in a row, now, CCDAP has generated flats that are ruined by heavy, heavy gradients. In all filters (twice the count in one corner than the opposite corner). The light frames generated earlier are fine.

I really need decent flats, obviously. I've attacheed the log. Can anyone figure out what's happening here? I have gotten perfectly good flats using CCDAP with this scope and camera before.

This message has been edited. Last edited by: Mark de Regt,

ccdap20070126_212557.log (33 KB, 77 downloads)

Hey, Mark.

Did you get good flats with the tracking off before? Unless I'm misinterpreting the log, it says that tracking was off?

Take care,
Bob

Yes, tracking was off when I got good flats. I turn tracking off so that the stars will streak rather than being in the same place, allowing me to get rid of them with a median combine.

I'm thinking that I may have an issue with the dome. DDW is driving me nuts, and it may be that the dome slit wasn't in the right place.

Mark,

Why turn tracking off? Just let CCDAP3 do it's thing and automatically dither the flats? This will take care of the stars that burn through. No need to smear the stars.

Paul Howard

Hi Mark,

Just as a thought, what did the NMSkies Cloud sensor read the morning you took the flats? Was it clear or were there clouds rolling through? I normally leave tracking on and dither 6 arcmin between each flat. That is plenty to remove any stars that show up when you do a sigma clip combine. If as you say the dome slit wasn't centered on the scope, this could very well have caused what you are seeing. Good luck figuring it out.