This is probably my new favorite image I've shot. Even though it's not one of my longest exposures, I absolutely love how the colors turned out on this, especially for a bicolor image. I particularly like the region of the top 'feather' of the helmet. It reminds me a lot of SHO Hubble Palette images. This nebula is also super strong in oxygen-iii, which I think helped contribute to the look (most nebulae have significantly weaker oxygen signal). I also made a [starless version using StarNet++](
https://i.imgur.com/QfxNQXn.jpg) for the hell of it. Captured on January 8th and 21st, and February 2nd, 2020 from a bortle 6 zone.
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**[Equipment:](
https://i.imgur.com/BYyK1wu.jpg)**
* TPO 6" F/4 Imaging Newtonian
* Orion Sirius EQ-G
* ZWO ASI1600MM-Pro
* Skywatcher Quattro Coma Corrector
* ZWO EFW 8x1.25"/31mm
* Astronomik LRGB+CLS Filters- 31mm
* Astrodon 31mm Ha 5nm, Oiii 3nm
* Agena 50mm Deluxe Straight-Through Guide Scope
* ZWO ASI-120MC for guiding
* Moonlite Autofocuser
**Acquisition:** 8 hours 0 minutes (Camera at Unity Gain, -20°C,)
* Ha- 49x360"
* Oiii- 31x360"
* Darks- 30
* Flats- 30 per filter
**Capture Software:**
* EQMod mount control. Captured using [N.I.N.A.](
https://nighttime-imaging.eu/) and PHD2 for guiding and dithering.
**[PixInsight Processing](
https://i.imgur.com/2NWXNSM.png):**
* BatchPreProcessing
* StarAlignment
* [Blink](
https://youtu.be/sJeuWZNWImE?t=40)
* ImageIntegration
* DrizzleIntrgration (2X, VarK 1.5)
* Super-Luminance stack created by stacking both Ha AND Oiii frames into a single image
**Ha/Oiii Stacks:**
* DynamicCrop
* DynamicBackgroundExtraction 2X
* STF stretch Applied via HistogramTransformation
* PixelMath to combine into single **bicolor image** (formula courtesy of /u/dreamsplease
> R=iif(Ha > .15, Ha, (Ha\*.8)+(Oiii*.2))
> G=iif(Ha > 0.5, 1-(1-Oiii)*(1-(Ha-0.5)), Oiii *(Ha+0.5))
> B=iif(Oiii > .1, Oiii, (Ha\*.3)+(Oiii*.2))
**Super-Luminance Stack:**
* DynamicCrop
* DynamicBackgroundExtraction 2X
* AutomaticBackgroundExtraction
* Deconvolution (only went with a mild decon; didn't want to oversharpen too much)
* TGV/MMT noise reduction
* ArcsinhStretch
* HistogramTransformation
**Bicolor Image:**
* Invert, SCNR, Invert, SCNR (to remove magenta and some green color casts)
* [Curves](
https://i.imgur.com/cCPsYrW.jpg)Transformation (lightness, hue saturation)
* AutomaticBackgroundExtraction
* CurvesTransformation (reduce greens)
* LRGBCombination with stretched Super-Luminance frame (with chrominance noise reduction)
* ACDNR (adaptive contrast driven noise reduction)
* Several CurveTransformations (for saturation and lightness, lightness masks used)
* LocalHistogramEqualization
* MLT noise reduction
* More CurveTransformations
* SCNR (remove oversaturated green from brighter parts of the nebula)
* LocalHistogramEqualization (more subtle this time)
* More CurveTransformations (for final lightness and color tweaking, with RangeMasks)
* ADVStarMask + MorphologicalTransformation (reduce star sizes)
* Resample to 90%
* Crop to 5760x4320 (from 8164x6119)
* Annotation
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