After four months of clouds, there was a short opportunity to capture some astro photons.
Conditions were not perfect (slight haze, the bright moon was rising two hours after session start, and clouds were expected a bit later), but skipping the session would have been much regretted.

I set up the following list on the ASIAIR before leaving the rig unattended for several hours:
* L - 12x 300s
* R - 12x 300s
* G - 12x 300s
* B - 12x 300s
* L - 56x 300s (this was overly optimistic, i.e. desperate)

Setting up everything (AM5, Sharpstar Z4, EAF, EFW, 2600MM/gain100, GS+120MM) worked without any issues and took about 45 minutes (getting out of the car until starting the capturing plan).
The camera was set up to use gain 100 ("HGS mode").
By coincidence, the meridian flip point was reached during guiding calibration, which resulted in an unexpected stop of the calibration process (and kept me puzzled for a few seconds).

I never managed to cool my ASI 2600MM below 0 degrees Celsius in summer. This time, cooling it to minus 10 degrees worked without issues.
After creating a -10-degree dark/bias library the next night, I also attempted to do the same for -20 degrees but never managed below -19.6 degrees with 100% cooling (ambient temp was around +5 degrees).

After four R frames, the moon went up and significantly lowered the image quality.
I expected this and decided to accept it since RGB would "only" be used for coloring.
And, of course, after a few of the second L frame shots, M31 went below the horizon, keeping the ASIAIR stuck in that position (I should have checked that).

Flats were taken the next morning in a dark room with the Lacerta Flatfieldbox (dimmed down using the PWM dimmer accessory).

For postprocessing (Siril), the following steps were taken:

• Per channel (L/R/G/B): calibration, registration, stacking, BG extraction
• Common registration (alignment) of the resulting four images
• RGB composition (L,R,G,B=luminance,red,green,blue)
• Photometric color calibration
• GHS stretching, black point adjustment
• Denoise
• Crop

The resulting image is way too blueish, but I did not touch any sliders.
Instead, the weather conditions during R/G/B capturing (rising moon and upcoming clouds) caused that.