So this is my third time shooting NGC 7380 (previous pics were from 2018 and 2020). This time around I decided to go with a different false-color palette (exact details below) compared to my prior true color and Hubble palette pics. Captured over 4 nights in Nov/Dec, 2023 from a Bortle 9 zone.

Places where I host my other images:

Flickr | Instagram

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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 for guiding

• Moonlite Autofocuser

Acquisition: 12 hours 48minutes (Camera at unity gain, -15°C)

• Ha - 33x360"

• Oiii - 52x360"

• Sii - 43x360"

• Darks- 30

• Flats- 30 per filter

Capture Software:

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

PixInsight processing:

Preprocessing

• BatchPreProcessing

• StarAlignment

• Blink

• ImageIntegration per channel per panel

• DrizzleIntegration (2x, Var β=1.5) per panel per channel

• StarAlignment in mosaic mode to align the two panels, then GradientMergeMosaic to combine them

Linear:

• DynamicBackground Extraction

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

• NoiseXterminator

• Duplicated images, to be used later for stars only processing

• STF applied via HistogramTransformation to bring nonlinear

Stars processing:

• Extracted stars-only pic using StarXterminator

• Pixelmath to make color SHO --> RGB image

• SpectroPhotometricColorCalibration (narrowband working mode)

• ArcsinhStretch + HT to bring nonlinear

• SCNR > invert > SCNR >invert to remove greens and magentas from stars

• Stars only pic saved for later addition to starless pic

Nonlinear:

• StarX to remove all stars

• PixelMath to create color image in OSH --> RGB palette

• PixelMath to make a second image using Jimmy’s Royal Palette:

  R = 0.3*Oiii+0.7*(Oiii^~(0.7*Ha+0.3*Sii))^1.2

  G = ((Oiii*Ha)^~(Oiii*Ha))*Ha + _((Oiii*Ha)^(Oiii*Ha))*Sii

  B = 0.9*Sii+Ha-Oiii

• PixelMath to blend OSH and Jimmy pics together 50:50

• LRGBCombination using stretched Ha as luminance

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

• another round of NoiseXTerminator

• Extract L --> LRGBCombination for chrominance noise reduction

• LocalHistogramEqualization

• More curves

• MultiscaleLinearTransform

• Relinearized narrowband and stars images to add in the stars only image

“unstretched” both images with histogramtransformation midtones set to 0.9999

pixelmath to just add those two images together

histogramtransformation to un-relinearize them by setting midtones to 0.0001

• Even more curves

• Resample to 60%

• annotation