Messier 51 (Whirlpool Galaxy)

Acquisition:

Bortle 7 skies
Nikon D5600 camera
ISO 400
Astro-Tech AT102ED refractor, 714mm focal length, f/7
HoTech 2" SCA field flattener (1X)
iOptron CEM26 mount
30s x 634 frames (5h 17m)

Processing:

Siril 1.2.1:

Crop to 3600 x 2700px
BQ Octantis' technique of white balance, background subtraction, and histogram conditioning
StarNet:
Star desaturation
Background:
Modified asinh transformation (4x)
Generalized hyperbolic transformation
Background extraction
Histogram adjustment
Stars:
Modified asinh transformation (4x)
Synthetic blue
Saturation

RawTherapee 5.9:

Luminance noise reduction

GIMP 2.10:

Luminance curve
Saturation