This nebula is also called the 'popped balloon nebula' and 'the garlic nebula'
This is certainly one of my longer projects, coming in at just under 50 hours of exposure time total. Due to how faint this target is I couldn't shoot it when the moon was up at all, so it took me over 3 months to get enough exposure time in on it. It was also pretty difficult to process, particularly when stretching, in order to bring out the faint details in the nebula without overstretching the noise and keeping the stars reasonably balanced (iirc I tried about 5 different stretching workflows on it before settling on the one described below). Captured over 19 nights from September through December, 2021 from a Bortle 6 zone.
**Places where I host my other images:**
[Instagram](https://www.instagram.com/leftysastrophotography/) | [Flickr](https://www.flickr.com/people/leftysastrophotography/)
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**[Equipment:](https://i.imgur.com/6T8QNsv.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:** 49 hours 54 minutes (Camera at Unity Gain, -15°C)
* Ha- 184x600"
* Oiii- 89x600" + 44x360"
> Accidentally had the wrong Oiii sequence template for a few nights, but it didn't seem to harm the stack by including the 360" data
* 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)
**Linear:**
* DynamicCrop
* AutomaticBackgroundExtraction
* DynamicBackgroundExtraction
* EZ Denoise per channel
**Stretching to nonlinear:** (per channel)
> Probably the hardest part of processing this image. I tried several other workflows before settling on this one, which I used for my photo of [sh2-216 earlier this year](https://www.reddit.com/r/astrophotography/comments/l57hmg/sh2216_the_largest_planetary_nebula_60_hours/).
* MaskedStretch to 0.1 background
* Starnet++ starmask made, subtracted from 0.3 Gray image and colvolved
* Previous image used as a mask to stretch nebulosity without stretching stars
* Previous two steps were repeated 2X with incremental HistogramTransformations
* One final unmasked histogramtransformation
**Combining Channels:**
* Monochrome Ha and Oiii images combined into a color image using [ForaxX's HOO palette](https://thecoldestnights.com/2020/06/pixinsight-dynamic-narrowband-combinations-with-pixelmath):
> R= Ha
> G= ((Oiii\*Ha)\^~(Oiii\*Ha))\*Ha + ~((Oiii\*Ha)\^~(Oiii\*Ha))\*Oiii
> B= Oiii
**Nonlinear:**
* Create Synthetic luminance with Pixelmath:
> Max(Ha, Oiii)
* LRGBCombination using synthetic luminance for chrominance noise reduction
* Shitloads of CurveTransformations to adjust lightness, saturation, contrast, hues, etc.
* MLT noise reduction
* LocalHistogramEqualization
* EZ Star Reduction
* even more curves
> probably a few other processes should go here that I'm forgetting about. I completely redid the nonlinear processing 3 times and didn't bother to save the image histories, so I'm going off memory for this.
* IntegerResample to 50%
* Annotation
lefty7283
