Shot this about a year ago and havent gotten around to processing it until now. I had shot it in tricolor SHO, but it [turns out there is no Oiii in this thing](https://i.imgur.com/MqBAobn.png), so the overall image looks a little more bicolor/monochrome than my usual tricolor pics. still like how it turned out though with the purple palette. Captured on January 8, 10, and February 14, 15th, 2022, from a Bortle 6 zone.
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**[Equipment:](https://i.imgur.com/ejpKkwU.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, Sii 5nm
* Agena 50mm Deluxe Straight-Through Guide Scope
* ZWO ASI-290mc for guiding
* Moonlite Autofocuser
**Acquisition:** 9 hours 30 minutes (Camera at unity gain, -15°C)
* Ha - 61x360"
* Oiii - 25x360"
* Sii - 26x360"
* Darks- 30
* Flats- 30 per filter
**Capture Software:**
* Captured using [N.I.N.A.](https://nighttime-imaging.eu) and PHD2 for guiding and dithering.
**PixInsight Processing:**
* BatchPreProcessing
* SubframeSelector
* StarAlignment
* [Blink](https://youtu.be/sJeuWZNWImE?t=40)
* ImageIntegration
* DrizzleIntegration (2x, Var β=1.5)
* DynamicCrop
* AutomaticBackgroundExtraction
* NoiseXterminator (Ha only)
* duplicated S H and O images, to be used for stars only procesing later
* Ran starXterminator on original images to remove stars
* STF applied via HistogramTransformation to stretch nonlinear
* PixelMath to combine monochrome Ha Oiii and Sii images into a color image with /u/jimmythechicken1's palette
> R = 0.3\*Oiii+0.7\*(Oiii\^~(0.7\*Ha+0.3\*Sii))\^1.2
> G = ((Oiii\*Ha)\^~(Oiii\*Ha))\*Ha + ~((Oiii\*Ha)\^~(Oiii\*Ha))\*Sii
> B = 0.9\*Sii+Ha-Oii
* LRGBCombination with stretched Ha as luminance
**Stars Only Processing:**
* Channelcombination to convert monochrome stacks into color image using SHO palette
* SpectroPhotometricColorCalibration (in narrowband mode. if i do this again in the future I may not even touch this)
* HSV Repair
* ran starX on a copy of this image, subtracted this residual from the original image to make a truly stars only image
* ArcsinhStratch + HistogramTransformation to stretch nonlinear
**Nonlinear processing:**
* combined starless pic with stars only pic using Jimmy's pixelmath
> mtf(~m,(mtf(m,Starless)+mtf(m,Stars)))
* Shitloads of CurveTransformations to adjust lightness, saturation, contrast, hues, etc.
* LocalHistogramEqualization
* some combination of deepSNR and NoiseX I can't remember
* colorsaturation
* more curves
* resample to 70%
* annotation
lefty7283
