VdB 152 - Reflection Nebula in Cepheus

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