The Bubble Nebula in SHO Hubble Palette ( Josh Woodward )

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The Bubble Nebula in SHO Hubble Palette

Imaging telescope or lens:Celestron C8 Starbright

Imaging camera:ZWO ASI 1600MM Cooled Pro

Mount:Orion (Synta) Atlas EQ-G

Guiding telescope or lens:Celestron C8 Starbright

Guiding camera:ZWO ASI 290MM mini

Focal reducer:Celestron Focal Reducer/Flattener x0.63

Software:PHD2 Guiding , Stellarium , EQMOD , DeekSkyStacker (DSS) , SharpCap , PixInsight 1.8 , StellariumScope , Seqence Generator Pro

Filters:ZWO Blue 1.25" , ZWO Green 1.25" , ZWO Red 1.25" , ZWO L 1.25"

Accessories:ZWO EFW 8x 1.25" , ZWO OAG , QHYCCD QHY PoleMaster , Rigel Systems nStep

Dates:Aug. 22, 2019 , Aug. 23, 2019

Frames:
ZWO Ha 1.25": 183x180" (gain: 300.00) -15C bin 1x1
ZWO OIII 1.25": 174x180" (gain: 300.00) -15C bin 1x1
ZWO SII 1.25": 164x180" (gain: 300.00) -15C bin 1x1

Integration: 26.0 hours

Darks: ~25

Flats: ~20

Flat darks: ~20

Avg. Moon age: 21.55 days

Avg. Moon phase: 56.31%

Bortle Dark-Sky Scale: 5.00

Temperature: 25.00

Basic astrometry details

Astrometry.net job: 2885559

RA center: 23h 20' 37"

DEC center: +61° 10' 30"

Pixel scale: 0.617 arcsec/pixel

Orientation: 269.872 degrees

Field radius: 0.350 degrees

Resolution: 3312x2396

Locations: backyard, Chico, CA, United States

Data source: Backyard

This is my fifth iteration of trying to create a satisfying Hubble Palette image of the Bubble Nebula.

I first registered the the images to Ha using Star Alignment. I then used Dynamic Crop to clip off stacking artifacts and coma in the corners. Next, I used Linear Fit to with Ha as the reference to calibrate SII and OIII. I then used ABE separately on OIII, Ha, and SII. I then combined the images using PixelMath.

With this version I went with a PixelMath combination of:

Red - SII * 0.8 + Ha*0.2
Green - Ha*0.85 + OIII*0.15
Blue - OIII*0.9 + Ha*0.1

I then did a 90% SCNR to remove the remaining green cast

I was having problems with a purplish background until I used Background Neutralization..
SHO images tend to err towards green because Ha overwhelms OIII and SII. To combat this, I adjusted the green hue towards orange/yellow using Curves hue adjustment. I then used Jon Rista’s NR techniques with TGV Denoise and MMT.

I stretched the image using Histogram. I used ACDNR to with a strong mask to remove the “black tail”. I used a mild Color Saturation to boost the color paying special attention to the light blue of the “Bubble”. I used HDRMT to draw out hidden details. Then Morphological Transformation to reduce star size. Lastly, I used Curves for sight contrast and saturation enhancements.