Quote:
Originally Posted by toryglen-boy
Thanks again Marc, ok, so the flat fielding is looking better, but is still not right, i had taken the today, after storing the OTA overnight indoors, although the orientation of the camera, and focuser where not changed, so this should be fine, right? or maybe i should take them at teh exact same time as the lights, i can see that the "cosmic string" in the image has a dark and light part, so maybe this moved, when i shifted the OTA
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The dust donust weren't corrected and are slightly offset so I reckon your focus wasn't the same when you shot the light frames and your flats. Interesting point about the halos still without the nose piece.
Maybe it's an internal reflection into the MPCC reflected from the CCD glass.