VdB 14/15 and SH2-202 in HaLRGB - 2 Panel Mosaic

Van den Bergh 14 & 15 along with SH2-202 in HaLRGB. This is a 2-panel mosaic from data I finished capturing a few months ago but hadn't had the time to sit down and process until now. I am properly proud of this image, more so than any of the others I have made since going remote. The stark contrast of the blue reflection nebula and the hydrogen alpha emission from the Sharpless cloud juxtaposed next to each other make this an extremely dynamic region.

 

I have not seen that many images of these objects in particular on Astrobin and thus wanted to shoot it in the hopes of inspiring others to make even better images of it in the future.

 

- Location: Remote Observatory (Bortle 1, SQM 21.99) near Fort Davis, TX

- Total Exposure Time: 77.9 Hours

 

Equipment:

- Scope: Esprit 100ED w/ 1x Flattener

- Imaging Camera: QHY 268M

- Filters: Chroma HaLRGB (36mm)

- Mount: Astro Physics Mach1GTO

- Guidescope: SVBony 50mm Guidescope

- Guide camera: ASI 120mm mini

- Focuser: Moonlite Nitecrawler WR35

- Accessories: Pegasus Ultimate Powerbox v2, QHY Polemaster, Optec Alnitak Flip Flat

 

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Software:

- N.I.N.A for image acquisition, platesolving, and framing

- PHD2 for guiding

- PixInsight for processing

 

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Acquisition:

- Ha: 314 x 5m (5nm)

- L: 500 x 3m

- R: 185 x 3m

- G: 174 x 3m

- B: 176 x 3m

- All images at Gain 56, Offset 25 (Readout mode 1) and -5C sensor temperature

- 20 flats per filter

- Master Dark, Flat & Bias from Library

- Nights: 9/26-9/28, 9/30-10/2, 10/12, 10/13, 10/20-10/23, 10/26-10/30, 11/2, 11/3, 11/5, 11/7/22

 

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Processing:

 

For each pair of masters per filter:

- DynamicCrop

- MureDenoise

- DynamicBackgroundExtraction

- ImageSolver script with distortion correction enabled to platesolve each panel

- MosaicByCoordinates script to create mosaic master templates

- PhotometricMosaic script to stitch panels into masters for each filter

 

RGB Processing (apply to each master):

- DynamicCrop to remove mosaic edges

- DynamicBackgroundExtraction

- StarAlign G/B/Ha to Red

- Combine RGB linear masters into color linear image with ChannelCombination

- DynamicBackgroundExtraction

- SpectrophotometricColorCalibration

- StarXterminator to remove stars for processing and save star_mask

- NoiseXterminator x2 for noise reduction

- BackgroundNeutralization with preview for color correction

- NoiseXterminator at 0.25 for further NR

- HistogramTransformation for initial stretch and then further green channel tweak

 

Create Continuum-Subtracted Image for non-linear Ha Addition:

- StarAlign Ha master to Red

- PixelMath to assign Red and Ha to HRR as RGB respectively

- BackgroundNeutralization using background preview and ColorCalibration to isolate Ha signal

- StarXterminator to remove stars from linear image

 

Luminance Processing:

- DynamicCrop

- DynamicBackgroundExtraction

- StarAlign to Red

- StarXterminator to remove and extract stars - save stars_only image

- GeneralizedHyperbolicStretch for intial stretch

- HistogramTransformation x3 for further stretch

- CurvesTransformation for contrast

- UnsharpMask with luminance mask applied to sharpen reflection tendrils

- ACDNR with luminance mask applied for slight noise reduction

 

Combine Luminance and RGB:

- LRGBCombination with chrominance NR enabled

- Extract luminance mask and CurvesTransformation to super stretch

- Apply luminance mask and invert mask

- MultiscaleMedianTransform with inverted lum mask for chrominance noise reduction

 

Add Ha to LRGB:

- NoiseXterminator on linear Ha image for noise reduction

- HistogramTransformation x3 to stretch

- CurvesTransformation for extreme contrast curve to suppress background and isolate Ha signal

- PixelMath to add Ha to LRGB

- ColorSaturation to saturate blue reflection nebulosity

 

Further Processing:

- CurvesTransformation for slight contrast adjustment

- HistogramTransformation x3 on RGB stars to stretch to non-linear

- Invert -> SCNR green -> invert to remove magenta from stars

- SCNR green on stars

- CurvesTransformation to saturate and bring up blue point for stars

- HistogramTransformation x2 on Luminance stars to match size of RGB stars

- LRGBCombination to combine Luminance and RGB stars with saturation at 0.35

- ColorSaturation to saturate blue stars

- PixelMath with re-linearization technique to combine stars with starless nebulosity

- NoiseXterminator for final noise reduction

- SCNR green to remove slight green tint

- MorphologicalTransformation with luminance star_mask applied for slight noise reduction

- CurvesTransformation for final green reduction/'c' curve adjustment, and contrast boost

- DynamicCrop to crop edges

- Save and export

Done