DWB 111 - The Propeller Nebula


submitted by Avatar lefty7283 edited

DWB 111 - The Propeller Nebula

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Avatar lefty7283 [OP]

Probably should've gotten more exposure time on this, but it was already *way* out of season. Captured over several nights in January 2024, from a Bortle 9 zone

Places where I host my other images:

Flickr | Instagram


  • 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: 10 hours 10 minutes (Camera at -15°C), Camera at unity gain.

  • Ha - 35x360"

  • Oiii - 31x360"

  • Sii - 35x360"

  • L - 200x120"

  • 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

  • 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

**Narrowband Linear:

  • Blur and NoiseXTerminator

  • Duplicated the images before stretching to be used for separate stars-only processing

  • STF applied via histogramtransformation to stretch nonlinear

Stars Only Processing:

  • StarXTerminator to make stars only image form each channel

  • PixelMath to combine star images (SHO palette)

  • SpectroPhotometricColorCalibration (narrowband working mode)

  • SCNR Green

  • ArcsinhStretch + HT to stretch nonlinear - to be combined later with starless pic


  • PixelMath to combine stretched Ha, Oiii, and Sii images into color image (SHO palette)

  • Invert > SCNR > invert > SCNR to remove greens and magentas

  • Shitloads of Curve Transformations to adjust lightness, hues, contrast, saturation, etc

  • LRGBCombination with stretched Ha as luminance

  • more curves

  • NoiseXterminator

  • LocalHistrogramEqualization (at small and large scales to target varying structures)

  • MLT for large scale chrominance noise reduction

  • Extract L --> LRGBCombination for smaller scale chrominance noise reduction

  • Pixelmath to add in the stretched stars only image from earlier

    This basically re-linearizes the two images, adds them together, and then stretches them back to before

    (Jimmy is a processing wizard when it comes to writing up this independent starless processing stuff)




  • more curves

  • Resample to 60%

  • Annotation