Sh2-204 (2026)

So this is my version of the emission nebula Sh2-204 located approximately 12,000 light-years away in the constellation of Camelopardalis. It is very large with sizes reported between 250 to 400 light-years across. The predominant gas is hydrogen with a lesser amount of sulfur and an even smaller amount of oxygen - my collection supports this as there did not seem to be any oxygen in any of the subexposures. The region also contains a lot of dust which with a larger field of view makes a nice frame. Unfortunately, my setup was not large enough to get the best parts of the dusty structures.

This is a very faint object and was a challenge (pain in the neck) to process. If you try this lots of data will be required and dark skies will help greatly especially for the dust. My Bortle 5 to 7 sky was a real challenge. I was not having any success bringing out the blue OIII until I used a PixInsight NB combination with RGB script and then it was more processing gymnastics. If I had to do this again from this location I would have done an HaRGB and skipped the SII and OIII.

Higher Quality:
https://www.astrobin.com/6pb6up/?nc=collection&nce=712

Sh2-204 (2026)
Dates: 12-11-25, 12-14, 12-16, 12-17, 12-21, 1-7, 1-8, 1-12, 1-15, 1-19, 1-20, 1-22, 1-23, 2-2, 2-4, 2-5
Camera: ZWO ASI1600MM-Pro
Telescope: Astro-Tech AT115EDT 115mm Refractor Telescope
Barlow: None
Focal Length: 805mm (644mm w/ FR)
f/7 (f/5.6)
Focal Reducer: 0.8x AstroTech Field Flatterner/Focal Reducer
Mount: Orion Sirius
Filter Wheel: ZWO
EFW 8 x 1.25"
Filter: Antlia Ha, OIII, SII, ZWO L, R, G, B
Focuser: ZWO EAF
Autoguiding: ASI120 Mini attached to an Agena 50mm Guide Scope/ZWO 60mm Guidescope
Exposure: Ha 249 x 300, OIII 192 x 300, SII 143 x 300, L 220 x 90, R 95 x 90, G 81 x 90, B 93 x 90  (60h 53m)

Gain: 139
Offset 20
Sensor Temp: -20 C
Processing: NINA, PixInsight, Photoshop, BlurXTerminator, StarXTerminator, NoiseXTerminator, GraXpert, Bill Blanshan Color Masks, Bill Blanshan Stretching, Topaz Denoise.

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