NGC7380, an open star cluster, lies in the constellation Cepheus 8000 light years away. The surrounding interstellar gas is displayed in false-color here. The warmer tones represent Hydrogen-alpha and Sulfur-II emissions while blues represent Oxygen-III emissions.

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) for Ha

Ft. Griffin State Historic Park, TX (Bortle 2) for Oiii and Sii

Dates: 7/19/20, 8/9/20, 8/10/20, 8/11/20, 8/12/20, 8/13/20,

Gain: 200 Offset: 50

Camera temp: -10C

Sii: 11x600" Astrodon 3nm 1.25"

Ha: 337x300" Astrodon 5nm 1.25"

Oiii: 12x600" Astrodon 3nm 1.25"

Total integration time: 31hr 55min

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

ImageIntegration

DrizzleIntegration

DynamicCrop

DBE

Luminance Processing:

Duplicated master Ha to use as the Luminance

Duplicated the image again to later use for stars

Used PixelMath and StarNet to stretch, remove stars, and then return to linear

Deconvolution

ArcsinhStretch

HistogramTransformation

LocalHistogramEqualization

MultiscaleLinearTransform

TGVDenoise

CurvesTransformation

Used PixelMath to insert stars from the duplicated master

MorphologicalTransformation to reduce star sizes

UnsharpMask to slightly sharpen stars

MultiscaleMedianTransform to smooth blotchy noise

HistogramTransformation

MultiscaleLinearTransform

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

Removed stars by stretching, running StarNet, and inverting the stretch to return to linear

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

HistogramTransformation to bring to non-linear

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

R: Sii

G: Ha

B: Oiii

Tonemap Processing:

CurvesTransformation with ColorMasks to balance colors

Invert>SCNR>Invert using a mask to remove magenta from background sky

MultiscaleMedianTransform to reduce blotchy noise

TGVDenoise

CurvesTransformation for more color balance

Combined Tonemap with Luminance using LRGBCombination:

CurvesTransformation for slight contrast

Resampled to 25% for web posting