For the first time since I started doing astrophotography I've processed a comet photo that I actually like. They're usually a bitch to stack/process because the comet moves relative to the background stars, but thanks to /u/aatdalt's [latest video](https://www.youtube.com/watch?v=SCMyGNZlx5o) I've finally been able to figure it out. Now I just gotta go through the half dozen other comets I've shot over the years but never processed...
Real excited that I managed to get the ion tail, despite the high light pollution. You can see some structure in it with an [aggressive stretch](https://i.imgur.com/6fAks8K.png), but this also brings out some residual star trails. Captured on the morning of January 28th, 2023 from my Bortle 8 apartment balcony.
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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-120mc for guiding
* Moonlite Autofocuser
**Acquisition:** 1 hour 32 minutes (Camera at half Unity Gain, -15°C)
* R - 62x30"
* G - 61x30"
* B - 61x30"
> [Exact exposure breakdown here](https://i.imgur.com/pXgopjI.png)
* 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](https://i.imgur.com/VCixUbx.png):**
> The flowchart/video above do a MUCH better job at explaining this than my bulleted list
* BatchPreProcessing
* StarAlignment
* [Blink](https://youtu.be/sJeuWZNWImE?t=40)
* CometAlign batch StarXterminator + ImageIntegration to make comet only image
* ImageIntegration to make stars only image
**Comet Only Processing:**
* Channelcombination to convert monochrome R, G, and B stacks into color image
* DynamicCrop
* Channel match to align the color channels together (this comet is BOOKING it)
* DynamicBackgroundExtraction
* HistogramTransformation to stretch nonlinear
* BackgroundNeutralization
* Several curves adjustments for lights, contrast, saturation, hues, etc
**Stars only Processing:**
* Channelcombination to convert monochrome R, G, and B stacks into color image
* DynamicCrop
* DynamicBackgroundExtraction
* SpectroPhotometricColorCalibration
* 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 comet pic with stars only pic using Jimmy's pixelmath
> mtf(~m,(mtf(m,Starless)+mtf(m,Stars)))
* noiseXterminator
* ColorSaturation (comet tail was a little too red for my liking originally)
* MLT for chrominance denoise
* Even more curves
* EZ star reduction + noise generator to add noise back into star reduced areas
* more color saturation
* even more curves
* annotation
lefty7283
