Apparently it's called the crescent nebula because that's what it looks like through a visual telescope. I think it looks more like a scrotum ¯\\\_(ツ)_/¯
This is my third time shooting the Crescent Nebula! I had first shot it [back in 2017](https://www.reddit.com/r/astrophotography/comments/7es9n1/c27_the_crescent_nebula/) when I still used a DSLR for astrophotography. I still use the same scope, but eventually upgraded to a monochrome astro cam, and this was my first target using Hydrogen alpha + Oxygen-iii narrowband filters [in 2019](https://www.reddit.com/r/astrophotography/comments/bumgk9/the_crescent_nebula_haoiii_bicolor/). This year I decided to shoot it again, although I combined this years data with the data from 2019 since my setup then was identical to how it is now. I did have to heavily crop in on this image due to differing camera rotations, but I ended up with a higher signal to noise ratio overall by combining the data. I also [made a starless version of this pic](https://i.imgur.com/XzCdtah.jpg) which better shows off the faint nebulosity, including the Soap Bubble Nebula in the bottom left.
Captured over 5 nights in May 2019 (Bortle 7) and 4 nights in May 2022 (Bortle 6)
**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/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:** 26 hours 5 minutes (Camera at Unity Gain, -15°C)
* Ha - 61x360" + 88x300"
* Oiii - 54x360" + 87x300"
* 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
* DynamicBackgroundExtraction
* EZ Decon
* NoiseXTerminator
* STF applied via HT to bring each image nonlinear
**Combining Channels:**
> really like how the colors turned out on this, especially the slight gold/yellow in the nebula compared to the red in the background
* Pixelmath to make RGB 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:**
* LRGBCombination with extracted L as luminance, used for chrominance noise reduction
* Shitloads of CurveTransformations to adjust lightness, saturation, contrast, hues, etc. with various masks
* NoiseXTerminator
* More Curves
* EZ star reduction
* NoiseGenerator to add noise into reduced star areas
* Even more curves
* ColorSaturation to better bring out the Oiii regions
* More NoiseX
* Resample to 80%
* Annotation
lefty7283
