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  • The Little Dumbbell Nebula gets its name because it kinda looks like a tinier version of the Dumbbell Nebla M27 (yes, a different palette was used for this pic). It's really tiny compared to the uncropped FOV. I'm a lot happier with this attempt at it, compared to my 2019 pic of M76 with the same equipment. I know It's a bit out of season rn but I needed something to shoot at the start of the night. The nebulosity itself is false color, but the stars are true color RGB. Captured over 10 nights in Feb/Mar 2024 from a bortle 9 zone (I could only get a couple hours max per night on it.

    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: 21 hours 6 minutes (Camera at -15°C), NB exposures at unity gain and BB at half unity

    • Ha - 99x360"
    • Oiii - 83x360"
    • R - 101x60"
    • G - 100x60"
    • B - 99x60"
    • 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 (to be later replaced by the RGB ones)
    • ArcsinhStretch to slightly stretch nonlinear
    • iHDR 2.0 script to stretch each channel the rest of the way.

    This is a great new pixinsight script from Sketch on the discord. here's the link to the repo if you want to add it to your own PI install.

    RGB Linear:

    • ChannelCombination to combine monochrome R G and B frame into color image
    • SpectroPhotometricColorCalibration
    • BlurXTerminator for star sharpening
    • HSV Repair
    • StarXterminator to generate a stars-only image
    • ArcsinhStretch + HT to stretch nonlinear (to be combined with starless narrowband image later)

    Nonlinear:

    • PixelMath to combine stretched Ha and Oiii images into color image (/u/dreamsplease's palette)

    R = iif(Ha > .15, Ha, (Ha.8)+(Oiii.2))

    G = iif(Ha > 0.5, 1-(1-Oiii)(1-(Ha-0.5)), Oiii (Ha+0.5))

    B = iif(Oiii > .1, Oiii, (Ha.3)+(Oiii.2))

    • NoiseX again
    • Shitloads of Curve Transformations to adjust lightness, hues, contrast, saturation, etc
    • LocalHistogramEqualization
    • UnsharpMask
    • More curves
    • ColorSaturation to slightly desaturate the purples
    • even more curves
    • Pixelmath to add in the stretched RGB stars only image from earlier

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

    (again, credit to Jimmy independent starless processing stuff)

    mtf(.005,

    mtf(.995,Stars)+

    mtf(.995,Starless))

    • Couple final curves
    • DynamicCrop waaaay in on the nebula
    • Annotation
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