Also pictured is M21! (the star cluster to the top left of the nebula)

Very pleased with how this one turned out! Despite guide camera issues for the first hour of the night, and horrific seeing/guiding error/HFR values, this somehow turned out decent. I also made a starless version which better shows the fainter/diffuse nebulosity.

Captured on April 20th, 2023 from the Deerlick Astronomy Village (Bortle 3)

Places where I host my other images:

Instagram | Flickr

---

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-120mc 290mc for guiding

• Moonlite Autofocuser

Acquisition: 2 hours 36 minutes (Camera at half Unity Gain, -15°C)

• L- 37x120"

• R - 14x120"

• G - 13x120"

• B - 14x120"

• Darks- 30

• Flats- 30 per filter

Capture Software:

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

PixInsight Processing

• BatchPreProcessing

• SubframeSelector

• StarAlignment

• Blink

• ImageIntegration

• DrizzleIntegration (2x, Var β=1.5)

Luminance Linear:

• DynamicCrop

• DynamicBackgroundExtraction

copied the image and ran starx on it. then ran DBE and output the background model as ‘model’. subtracted this from the original using PixelMath:

$T * med(model) / model

• BlurXTerminator (i caved)

• NoiseXterminator

• ArcsinhStretch+HistogramTransformation to bring nonlinear

RGB Linear:

• DynamicCrop

• DynamicBackgroundExtraction

same DBE process as above

• Blur+NoiseX

• ChannelCombination

• SpectrophotometricColorCalibration

• HSV Repair

• AcrsinhStretch + HistogramTransformation to stretch nonlinear

Nonlinear:

• added stretch luminance to stretched RGB via LRGBCombination

• DeepSNR

• SCNR green

• shitloads of CurveTransformations to adjust hue, lightness, saturation, etc. (some with star masks)

• Extract L --> LRGBCombination again for chrominance noise reduction (inverted L image used as mask)

• more curves

• LocalHistogramTransformation

Two round of this: one at kernel radius 16 for the finer ‘feathery’ details and one at 254 for larger structures

• even more curves

• BlurXTerminator (star reduction only)

• DarkStructureEnhance

• guess what more curves

• ColorSaturation

• final curves

• Resample to 70%

• DynamicCrop again

• annotation