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:

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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-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