Issue with ASI1600MC-Cool and DSS

tango01

Hello, I hope someone here or Sam can help me with an issue I am having with my new ASI1600MC-Cool when using DSS. The issue is that when I use darks and/or bias images in several instances I end up getting awfully looking histograms and related image with short red streaks. However, this is not a consistent issue. I attached an image that on the top shows a good output from processing images of the Helix Nebula + Darks+bias+flats. The bottom image shows an ugly output of exactly the same process using the same darks+bias+flats than in the Helix Nebula case (so the only difference are the light frames). All images are configured as RGB24 fits files with software bin2 and a sensor temperature of -10C.

Any idea what may be going on and how to set up DSS parameters to solve this issue?

By the way, when opening the fits files from the Bubble Nebula in fits liberator they all look OK and not particularly different to those of the Helix nebula. Also if I process lights and flats of the Bubble Nebula without darks and bias then, the resulting image of DSS is OK (as OK it could be without darks and bias).... Thank you.

tango01

By the way, I should have added that all lights both from Helix and Bubble had the same setup (e.g. unity gain and 150 sec. exposures)

einari

Those look like hot pixel effect.

Did you use same gain/offset values with both lights (and calibration frames) ?

Also was the stacking method same - average, sigma stacking ?

You can correct those with cosmetic correction (in DSS), but darks should take care of them anyway.

Didn't know you could bin colour camera images successfully.

tango01

Yes, settings for lights were exactly the same in all regards, even exposure time. I did this so I could use the same calibration frames. So, the not only the settings of the light frames are the same but the calibration frames were the same files.

Unfortunately, this is not a cosmetic issue. If you look at the ugly histogram, you will see that the red is just a thin spike which is representing the fact that all of the red channel information was erased by the calibration process and replaced instead by many short streaks.

So anyone or Sam has any idea what may be going on here. My concern is that the problem may not be with the calibration frames but with the light frames although in fits liberator they look good. I tried playing with fits settings in DSS but the result is always the same.

tango01

Also, DSS stacking settings in both cases were exactly the same.

tango01

I have found out that I have the same ugly result after stacking images from the crescent nebula on DSS but since the lights configuration is different it is more difficult to make a direct comparison. Still the problem is that darks and bias calibration seems to be erasing the red channel data and adding red streaks all over the resulting image.