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NGC 7331 and Stephan's Quintet

NGC 7331 and Stephan's Quintet

From dark-sky site (Bortle 2-3) in September 2023, but with heavy dew and technical problems cutting it short.


Bortle 2-3 skies
Nikon D5600 camera (unmodified)
ISO 200
Astro-Tech AT102ED refractor, 714mm focal length, f/7
HoTech 2" SCA field flattener (1X)
iOptron CEM26 mount
30s x 197 frames (1h 38m)


Siril 1.2.1:

2X drizzle during stacking
Crop to 9000x6750px
BQ Octantis' procedure of white balance, background subtraction, and histogram conditioning
background: modified arcsinh stretch (6x), background extraction, saturation
stars: modified arcsinh stretch (5x), saturation

RawTherapee 5.9:

L*a*b chrominance noise reduction
Luminance noise reduction

GIMP 2.10:

Luminance curve

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