VdB 152 - Reflection Nebula in Cepheus

The noise reduction on this is spot on, nice!

Permanently Deleted

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

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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