This chunk of sky in the constellation Cassiopeia is quite busy with nebula. You can find the impressive structure of the Bubble Nebula in the lower left, and the Lobster Claw in the upper right of the image. The semi-circle of red hydrogen dust on the left edge is the nebula Sh2-161, with the small but bright nebula NGC7538 sitting on the upper left.

This false-color image shows the Hydrogen and Sulfur as the warmer tones and Oxygen as blue.

Equipment:

OTA: William Optics GT81 w/0.8x reducer (382mm fl at f/4.7)

74mm aperture stop-down ring (brings scope to f/5.2)

Mount: Orion Sirius EQ-G (HEQ-5)

Guidescope: Orion 50mm guidescope

Guiding camera: Orion StarShoot Autoguider

Imaging camera: ZWO ASI1600MM-Cool

Accessories:

DeepSkyDad Autofocuser AF1

QHYCCD PoleMaster

Software:

SGP

PHD2

CdC

PixInsight

Acquisition:

Location: Flower Mound, TX (Bortle 7)

Dates: 8/19/19, 8/20/19, 9/3/19, 9/4/19, 9/5/19, 9/6/19, 9/7/19

Gain: 200 Offset: 50

Camera temp: -10C

Ha: 155x300" Astrodon 5nm

SII: 93x600" Astrodon 3nm

OIII: 89x600" Astrodon 3nm

Total integration time: 43hr 15min

64x darks per calibration (master from library)

30x flats per calibration

200x bias per calibration (master from library)

Preprocessing:

Batch PreProcessing script to generate calibrated images

StarAlignment

LocalNormalization

ImageIntegration

DrizzleIntegration

DynamicCrop

DBE

Luminance Processing:

Duplicated the master Ha to use as the luminance

Deconvolution

ArcsinhStretch and HistogramTransformation to bring to non-linear

Created a duplicate starless version using StarNet++

Combined the starless version with the image using PixelMath expression "F=0.4; (1-(1-$T)*(1-s)*F)+($T*~F)" followed by the same function but with F=0.2, (s=starless photo).

LocalHistogramEqualization

MultiscaleLinearTransform for sharpening

MorphologicalTransformation for star size reduction

UnsharpMask to harden up reduced stars

Preparing separate Sii, Ha, and Oiii linear masters for tonemapping (applied to each master individually):

TGV & MMT noise reduction (via Jon Rista's method)

ArcsinhStretch and HistogramTransformation to bring to non-linear

Removed stars via StarNet++

LinearFit to Ha

Combined prepared Sii, Ha, and Oiii masters with ChannelCombination:

R: Sii

G: Ha

B: Oiii

Tonemap Processing:

Invert > SCNR Green > Invert to remove magenta

Several a/b channel CurvesTransformations using ColorMasks to alter the colors to an aesthetically pleasing palette

HDRMultiscaleTransform on the Bubble

SCNR green on the background

CurvesTransformation to balance colors

HistogramTransformation

Combined Tonemap with Luminance using LRGBCombination:

HistogramTransformation to balance colors

CurvesTransformation for slight contrast

Resampled to 25% for web posting