Went to visit my future in-laws this past weekend and and took advantage of their dark skies and (fairly) new moon. Wanted to shoot other targets throughout the night but fog or clouds came in every night around midnight. I'd consider this image an improvement from the last time I shot M33 [back in 2018](https://www.reddit.com/r/astrophotography/comments/9n9ku9/m33_the_triangulum_galaxy_from_the_2018_peach/).
This image was taken with a monochrome camera through filters for luminance (all visible light), red, green, blue, and Hydrogen-alpha (656nm), which were combined into a tue color image. The Hydrogen-alpha was combined with the RGB data (described below) to enhance the hydrogen nebulae in the galaxy (red splotches in the spiral arms). Captured on October 8-10 from a bortle 4 zone (Ha data from my bortle 6 driveway on the 12th).
**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-290mc for guiding
* Moonlite Autofocuser
**Acquisition:** 11 hours 53 minutes (Camera at Unity Gain, -15°C)
* Lum - 103x180"
* Ha - 16x300"
* Red - 36x180"
* Green - 36x180"
* Blue - 36x180"
* 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/GpSMAvh.png):**
* BatchPreProcessing
* SubframeSelector
* StarAlignment
* [Blink](https://youtu.be/sJeuWZNWImE?t=40)
* ImageIntegration
* DrizzleIntegration (2x, Var β=1.5)
* DynamicCrop
* DynamicBackgroundExtraction
**Luminance:**
* EZ Decon + Denoise
* ArcsinhStretch + histogramtransformation to bring nonlinear
**RGB:**
* ChannelCombinaiton to combine monochrome R, G, B stacks into color image
* PhotometricColorCalibration
* SCNR green
**Adding Ha:**
> I followed this tutorial which had great results [on my last HaLRGB galaxy pic](https://www.reddit.com/r/astrophotography/comments/ml2os3/m51_the_whirlpool_galaxy_in_halrgb/):
> http://www.arciereceleste.it/tutorial-pixinsight/cat-tutorial-eng/85-enhance-galaxy-ha-eng
* PixelMath to make Clean Ha. This effectively [isolates just the Ha regions](https://i.imgur.com/Aob3UEO.png) from the red continuum spectrum
> Ha-Q * (Red-med (Red))
> Q=0.08
* PixelMath to combine Clean Ha
* PixelMath to add Ha to RGB image ($T)
> R= $T+B*(Ha_Clean - med(Ha_Clean))
> G= $T
> B= $T+B\*0.2*(Ha_Clean - med(Ha_Clean))
> B=3
**HaRGB:**
* HSV Repair
* ArcsinhStretch + histogramtransformation to bring nonlinear
**Nonlinear:**
* LRGBCombination with nonlinear L as luminance
* LRGBCombination again with galaxy masked, chrominance noise reduction applied to background
* HistogramTransformation to lower black point
* ColorSaturation to slightly desaturate Ha regions (clean Ha mask used)
* Shitloads of [Curve](https://i.imgur.com/iPmMDHp.jpg)Transformations to adjust lightness, contrast, colors, saturation, etc. (various masks used)
* LocalHistogramEqualization
* ACDNR
* Extract L channel > LRGBC again for chrominance noise reduction in the galaxy itself
* EZ StarReduction
* NoiseGenerator to add noise back into reduced stars
* More Curves
* Another round of LHE, smaller kernel radius this time
* Even more curves
* DynamicCrop to 16:9 aspect ratio
* Resample to 60%
* Annotation
lefty7283
