Space is cool

Yippie my comment never posted from last night! here’s the writeup:

Decided to give this one a reshoot under darker skies. My shot of it from 2019 had a lot more light pollution and less exposure time than this pic. M46 also has a small planetary nebula, NGC 2438, in the cluster. Captured on November 23rd, 2025 from a bortle 3 zone (Deerlick Astronomy village)

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: 1h 14m minutes (Camera at -15°C)

• L - 20x90"

• R - 10x90"

• G - 10x90"

• B - 9x90"

• 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

linear:

• 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

• BlurXterminator (correct only)

• STF applied via HistogramTransformation to stretch nonlinear

• Channelcombination to make color image from RGB stacks

• SpectrophotometricColorCalibration

• HSV Repair

• ArcsinhStretch + HistogramTransformation to stretch L and RGB images nonlinear nonlinear

• Slight curves saturation boost for the RGB image

Nonlinear processing:

• LRGBCombination with stretched L image as luminance

• DeepSNR noise reduction

• Lots of curve transformations

• Slight SCNR to remove greens from some stars

• more curves

• Resample to 65%

• Annotation