1y ago

M42 - The Orion Nebula

Equipment details:

Mount: OpenAstroMount by OpenAstroTech
Lens: Sony 200-600 @ 600mm f/7.1
Camera: Sony A7R III
Guidescope: OpenAstroGuider (50mm, fl=163) by OpenAstroTech
Guide Camera: SVBONY SV305m Pro
Imaging Computer: ROCKPro64 running INDIGO server

Acquisition & Processing:

Imaged and Guided/Dithered in Ain Imager
420x30s lights, 40 darks, 100 flats, 100 biases, 100 dark-flats over two nights
Prepared data and stacked in SiriLic
Background extraction, photometric color calibration, generalized hyperbolic stretch transform, and StarNet++ in SiriLic
Adjusted curves, enhanced saturation of the nebula and recombined with star mask in GIMP, desaturated and denoised background

This is my first time doing a multi-night image, and my first time using SiriLic to configure a Siril script. Any tips there would be helpful. Suggestions for improvement or any other form of constructive criticism are welcome!

4 comments

Wow, this is great!
Thanks for including your equipment and process.

Looks great overall! I think you may want to increase your dither size (or do them more often), as there's a hint of raining noise when pixel peeping. Also if your tracking allows for some longer subs, you could try to HDR those with your 30" exposures and bring out some of the fainter parts of the nebula
- Thank you for the feedback!
  I think you may want to increase your dither size (or do them more often)
  Good catch! What happened was that I forgot to tick the box to enable dithering on the first night, so the first ~180 subs or so had no dithering at all, which definitely caused the pattern noise. That said, I'd be interested to hear if you know of a rule of thumb for dithering settings (i.e. how frequently should you dither, and how many pixels). When I was dithering on the second night, I dithered every 2 frames by 2 pixels, but I more or less picked those values arbitrarily.
  Also if your tracking allows for some longer subs, you could try to HDR those with your 30" exposure
  Gotcha, I'll give that a try next time. I'm shooting with an unmodified and unfiltered camera from an urban area (Bortle 7-8) so I figured longer exposures wouldn't help too much, but it sounds like it might still be worthwhile. Thanks for the tip!
  
  If I’m shooting just one filter I usually dither every 4 frames, but most of the time I loop LLLRRGGBB > dither or HaHaOiiiOiiiSiiSii> dither. Imo dithering every 2 frames is a lot as you’ll spend a lot of time waiting for it to settle and not actively imaging.