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  • VdB 152 is technically just one part at the end of the dark nebula, and there are a number of other cataloged structures in this image. Captured from August 16-25, 2023. Broadband data from a Bortle 3 zone (Deerlick astronomy village), Ha from Bortle 9.

    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: 30 hours 15 minutes (Camera at -15°C)

    BB exposures at half unity gain (76/15), Ha at unity gain (139/21)

    • Ha - 102x600"
    • L - 200x120"
    • R - 70x120"
    • G - 70x120"
    • B - 68x120"
    • 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 per panel
    • DrizzleIntegration (2x, Var β=1.5)
    • Dynamic Crop
    • DynamicBackgroundExtraction

    Luminance Linear:

    • BlurXterminator
    • NoiseXterminator
    • ArcsinhStretch + HistogramTransformation to stretch to nonlinear

    Ha Linear:

    These steps largely follow the ones in NightPhoton's advanced narrowband combination guide.

    • Combine Ha with Red channel (HRR palette)
    • BackgroundNeutralization
    • ColorCalibration
    • StarXterminator to completely remove stars
    • PixelMath to subtract red continuum spectrum, leaving just Ha signal
    • HistogramTransformation to stretch nonlinear
    • NoiseXterminator + a little concolution
    • CurvesTransformation to adjust black point/contrast

    differing from the guide above, the background was a dark gray rather than clipped to black since this is more faint structure addition than bright structure

    RGB Linear:

    • SpectrophotometricColorCalibration
    • Slight SCNR Green
    • HSV repair
    • ArcsinhStretch + HistogramTransformation to stretch to nonlinear

    duplicate stars only was made and stretched to nonlinear using a less aggressive arcsin+HT for star addition later

    Nonlinear Processing:

    • Various curve adjustments for lightness, contrast, hue, saturation, etc (with varying lum/star masks)
    • LRGBCombination using stretched L as luminance
    • DeepSNR
    • More curves
    • PixelMath to add stretched Ha per the advanced narrowband guide above
    • BlurXterminator for star reduction

    Next few steps kinda follow along with this independent starless processing tutorial for manually combining stars via re-linearization

    • StarXterminator
    • HistogramTransformation to unstretch (also applied to duplicate stars early image from earlier)
    • PixelMath to combine starless + stars only images
    • HT to stretch everything back to nonlinear
    • Guess what more curves
    • MultiscaleLinearTransform for chrominance noise reduction
    • LocalHistogramEqualization (2 rounds of this at scales 68 and 384 with lum masks)
    • ColorSaturation to selectively saturate reds
    • Even more curves
    • Resample to 70%
    • Annotation