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Messier 13 through haze/smoke/clouds of June 2023

Messier 13 through haze/smoke/clouds of June 2023

Mostly through smoky/hazy skies (from Canada fires), with occasional Moon and clouds as bonus obstacles!

The galaxy at the top left is NGC 6207, around 50 million light-years away.


Bortle 7 skies (under good conditions)
Nikon D5600 camera
ISO 200
Astro-Tech AT102ED refractor, 714mm focal length, f/7
HoTech 2" SCA field flattener (1X)
iOptron CEM26 mount
30s x 386 frames (3h 13m)


Siril 1.2.1:

Crop to 4000 x 3000px
BQ Octantis' technique of white balance, background subtraction, and histogram conditioning
Borodog's "synthetic blue" channel (B = 2*G - R)
Star desaturation
Modified arcsinh stretch
Background extraction

RawTherapee 5.9:

L*a*b CL curve (to reduce background chroma noise)
Luminance noise reduction

GIMP 2.10:

Luminance curve
Temperature reduction

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