A few years ago I shot [just the core](https://live.staticflickr.com/65535/50619661997_0ea7a84b04_o.png) of NGC7822, and I've decided to reshoot it as a 2 panel mosaic to get some of the outer structures. The whole nebula is [actually pretty big in the sky](https://i.imgur.com/ojII7b5.png) (over 3 degrees!), but I did not want to deal with processing another 8+ panel mosaic to fit the whole thing.
Captured over 23 nights from September through November, 2023 from a Bortle 9 zone.
**Places where I host my other images:**
[Flickr](https://www.flickr.com/people/leftysastrophotography/) | [Instagram](https://www.instagram.com/leftysastrophotography/)
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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:** 51 hours 30 minutes (Camera at -15°C)
* Left panel:
* Ha - 54x360"
* Oiii - 130x360"
* Sii - 101x360"
* Right Panel:
* Ha - 46x360"
* Oiii - 94x360"
* Sii - 90x360"
* 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:**
**Preprocessing**
* BatchPreProcessing
* StarAlignment
* [Blink](https://youtu.be/sJeuWZNWImE?t=40)
* ImageIntegration per channel per panel
* DrizzleIntegration (2x, Var β=1.5) per panel per channel
* StarAlignment in mosaic mode to align the two panels, then GradientMergeMosaic to combine them
**Linear:**
* DynamicBackground Extraction
> duplicated each image and removed stars via StarXterminator. Ran DBE with a shitload of points to generate background model. model subtracted from original pic using the following PixelMath (math courtesy of /u/jimmythechicken1)
> $T * med(model) / model
* BlurXTerminator
* NoiseXterminator
* STF applied via HistogramTransformation to bring nonlinear
**Nonlinear:**
* PixelMath to combine stretched narrowband masters into color image
> SHO --> RGB (classic Hubble Palette)
* removed stars and processed stars-only image separately with invert>SCNR and curve adjustments, to be added to starless image later.
* HistogramTransformations to adjust channel intensities
* Invert > SCNR > Invert to remove magentas
* CurveTransformations for slight hue adjustments
* LRGBCombination using stretched Ha as luminance
* shitloads of CurveTransformations to adjust hue, lightness, saturation, etc. (some with lum masks)
* MLT chrominance noise reduction
* NoiseXTerminator
* LocalHistogramEqualization
> Two round of this: one at kernel radius 16 for the finer 'feathery' details and one at 512+ for larger structures
* More curves
* Relinearized narrowband and stars images to add in the stars only image
> "unstretched" both images with histogramtransformation midtones set to 0.9999
> pixelmath to just add those two images together
> histogramtransformation to un-relinearize them by setting midtones to 0.0001
* ColorSaturation
* Even more curves
* Extract L > LRGBCombination for some chrominance noise reduction
* Slight SCNR to remove some greens from the bright parts of the nebula
* DynamicCrop to remove a few artifacts around the edge where the panels overlap
* Resample to 60%
* annotation
* further downsampled 50% for lightbucket
lefty7283
