I always had problems calibrating out the starburst typical of 183M chips. Finally I managed to master it by playing with offsets during frame capturing of frames and manually tweaking pedestal during calibration itself. But now something very strange happened. Dark subtraction suddenly stopped working completely or it subtracts very little of the starburst. I tried literally every possible combination of both dark integration settings and calibration settings with no avail. Then I for giggles tried to use master dark as master flat and voila, it calibrated the image correctly. Any idea what might be going on? I'm completely lost. thx.
Camera: Altair Astro Hypercam 183M Cooled
Darks and Lights:
700s exposure time
32 black offset
8C temperature - I couldn't go cooler because of dew buildup
Combination method: average
Weights: don't care
Rejection - all combinations and no rejection
I even tried only one dark subframe as master dark and it behaves the same as integrated one.
Optimize on, threshold 3.0
When I use dark as flat I have to set pedestal to 50 in order to get it work properly. Everything has been shot with offset 32 however. Bu I'm already used to manual pedestal tweaking.