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M31 - Andromeda Galaxy - My second LRGB with the ASI183MM-Pro

astrophotography CMOS dso imaging filters refractor
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#1 Kevin Thurman

Kevin Thurman

    Mariner 2

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Posted 27 September 2020 - 02:45 AM

I recently posted my Pleiades image here and M31 was the other target from that same dark(er) sky trip. I got about twice as much data on this target, though, and I think it shows in how much I could get away with as far as sharpening. I've been at it all day, so I may have gone overboard with it. I'll give it a look after a good night's rest before publishing to social media. Let me know what you all think!

I was pleased with how much dust I could squeeze out around the core as well as around M110. I experimented with HDR but I didn't like the unnatural look, so all I did was mask the core before sharpening. That lead to a great compromise between core detail and natural brightness. Saturation was another tough task. I've seen everything from practically monochrome to a cartoon in how people do it. My philosophy for the saturation was to saturate enough that the various components of the galaxy stand out but not to make it too colorful. For example, the blues represent areas with dense hot star populations while red is where the nebulae are. It's saturated just enough to see those as distinct regions but not so much that it doesn't feel natural. I may add some Ha data to the red channel if and when I start getting narrowband filters.



Quick technical card here, also on astrobin:

Shot with a RedCat 51 and an ASI183MM on an iOptron SkyGuider pro with the ZWO mini guide kit.
Luminance: 133x 120s @ gain 0
RGB: 25 each 180s @ gain 130

Did all the processing and stacking in PixInsight this time. Starting to develop a workflow there.

First I made several masks. Masks for the cores of the galaxies, for the bright stars, for the small stars, and for all stars. These masks would be used in some form for just about every process I did. Next I combined RGB channels, balanced out the color, and worked on their noise. Next I worked on the lum channel to smooth out the grain and eek out whatever detail I could with unsharp mask and deconvolution. Then I went nonlinear and used LRGB combination. then I did some final sharpening with unsharp mask, a dash of saturation, and a final subtle stretch. It doesn't sound like much, but I did lots of trial and error and went through the whole process twice as the first time was not as good as I knew it could be.

Thanks for looking.

Edited by Kevin Thurman, 27 September 2020 - 02:49 AM.

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#2 WoodlandsAstronomer


    Vostok 1

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Posted 27 September 2020 - 04:36 AM

Thanks Kevin, great looking image, well done in capture and post. I’m constantly amazed by that little RedCat, it truly is a portable dark site marvel for larger fields!
  • Kevin Thurman likes this

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