Another image from my end of the year processing spree! I'm not entirely sure where the lion is in here, but it sure looks neat. I last shot this back in 2021, and overall I think this new go at it is a lot better color and noise wise. The region in the top left of the frame is incredibly rich in Oiii gas, which gives it a very distinct color difference from the rest of the nebula (no dynamic narrowband combination needed!). Captured over a shitload of nights from Sep-Nov, 2024 from a bortle 9 zone.

Places where I host my other images:

Flickr | Instagram

Equipment:

• 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: 65 hours 45 minutes (Camera at -15°C), unity gain

• Ha - 111x600"

• Oiii - 141x600"

• Sii - 130x600"

• R - 42x60"

• G - 42x60"

• B - 41x60"

• Darks- 30

• Flats- 30 per filter

Capture Software:

• Captured using N.I.N.A. and PHD2 for guiding and dithering.

PixInsight Preprocessing:

• BatchPreProcessing

• StarAlignment

• Blink

• ImageIntegration per channel

• DrizzleIntegration (2x, Var β=1.5)

• Dynamic Crop

• DynamicBackgroundExtraction

  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

Narrowband Linear:

• Blur and NoiseXTerminator

• StarXterminator to completely remove stars from each Ha, Oiii, and Sii image

• HistogramTransformation to stretch nonlinear

Broadband/RGB stars linear:

• ChannelCombination to make color image from R G and B stacks

• StarX (correct only)

• SpectrophotometricColorCalibration (narrowband working mode)

• HSV repair

• StarXterminator to extract a stars-only image (to be used going forward)

• arcsinhstretch

• scnr > invert > scnr > invert to remove greens and magentas

• HistogramTransformation

• (combined with starless pic later on)

Nonlinear:

• PixelMath to combine monochrome Ha Oiii and Sii images into a color image with SHO --> RGB, respectively

• HistogramTransformation to adjust red green and blue color channels separately (basically stretched R and B, and toned the G down some)

• Slight SCNR green

• NoiseXterminator

• LRGBCombination using stretched extracted L channel as luminance

• Shitloads of Curve Transformations to adjust lightness, hues, contrast, saturation, etc

• LocalHistogramEqualization (two rounds of this. one at kernel radius 16 for small scale detail, and one at 500 for large structures)

• More curves

• Pixelmath to add in the stretched RGB stars only image from earlier

  This basically re-linearizes the two images, adds them together, and then stretches them back to before. More info on it here)

  mtf(.005,

  mtf(.995,Stars)+

  mtf(.995,Starless))

• guess what more curves

• DynamicCrop again (I fucked up the framing a lil and had a lot of empty space towards the bottom)

• Resample to 75%

• Annotation