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  • So technically 32 Cygni is just the bright star in the pic, and the rest of it is just hydrogen gas floating around in space. The constellation Cygnus has a ton of this hydrogen-alpha gas floating around, and I kinda just pointed at a semi-random spot in the constellation to get a pic. Although this was taken with an Ha filter, the stars are true color RGB, and I mapped the Ha channel to red so it closely resembles the actual color of hydrogen-alpha. Also for those curious here is a starless version that better shows the faint nebulosity/structures. Also pls ignore the crunchiness around 32 Cyg itself, it's an artifact of my camera's microlensing + the star removal program I use. Captured over like a dozen nights in December 2024 from a bortle 9 zone.

    Places where I host my other images:

    Flickr | Instagram

    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-290mc for guiding
    • Moonlite Autofocuser

    Acquisition: 29 hours 18 minutes (Camera at -15°C), unity gain

    • Ha - 161x600"
    • R - 51x60"
    • G - 59x60"
    • B - 48x60"
    • 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
    • StarXterminator to completely remove stars from each the image
    • HistogramTransformation to stretch nonlinear (calling this the Ha image now)

    Broadband/RGB linear:

    • ChannelCombination to make color image from R G and B stacks
    • StarX (correct only)
    • SpectrophotometricColorCalibration

    (duplicated image at this point, to be used for stars only processing later)

    • StarX to completely remove stars (at this point it's just background, with a little bit of signal in the R channel)
    • Blended unstretched Ha image into the red (and a little bit of the blue channel) with this pixelmath:

      R = $T+B(Ha- med(Ha))

      G = $T

      B = $T+B0.2(Ha- med(Ha))

      honestly can't remember what I used for the B constant, but the default is 2 in my pixelmath ¯(ツ)_/¯

    • HistogramTransformation to stretch nonlinear (calling this the Starless image now)

    Stars only processing:

    • HSV repair to fix blown out star cores
    • StarXterminator to generate an image containing only the stars (without any background)
    • ArcsinhStretch + Histogramtransformation to stretch nonlinear (Calling this the Stars image now)

    Nonlinear:

    • LRGBCombination to add the stretched Ha image to the stretched Starless image as a luminance layer
    • NoiseXterminator
    • Background neutralization
    • Several curve transformations to adjust lightness, contrast, saturation, color balance, etc
    • LocalHistogramEqualization
    • Another round of noiseX
    • Pixelmath to add in the stretched RGB Stars image from earlier

      This basically re-linearizes the two images, adds them together, and then stretches them back to before. More info on it here)

      mtf(.005,

      mtf(.995,Stars)+

      mtf(.995,Starless))

    • few more curve adjustments
    • FastRotation 180 degrees (pic was originally upside down)
    • DynamicCrop again (just a little bit)
    • Resample to 60%
    • Annotation