congratulations to your ASI2600, this a very good start in CMOS-imaging. I have got some experience with ASI cameras within the years, mostly good.
I got a gallery on my website with images sorted by camera:
I got my ASI2600 some weeks ago and I used it in three whole nights from now.
What can I say?
The cooling is not as powerful as for the ASI1600 or ASI183. I operate these cameras at -20°C, this is fixed with the intend to reach this temperature around the year here in Germany. I decided to use -10°C for the ASI2600 because of the the same manner.
I also found that the temperature regulation oscillates within 0.8°C (peak-to-valley) around the setting temperature (no disturbing wind). I have not checked if this happens with the ASCOM driver too.
My second image I made was from a suburban site, but the object is always very low in the sky here. I used gain=100 and 4min subs. IC4592.jpg
I made two Masterbias and Masterdark (4min), one for gain=0 and one for gain=100. I will use gain=0 in the future for star clusters.