PN G75.5+1.7 - The Soap Bubble Nebula (wadeh237)

PN G75.5+1.7 - The Soap Bubble Nebula

The Soap Bubble Nebula in Cygnus.

This is an interesting target because of its location embedded in bright clouds of hydrogen. Despite being in one of the most photographed areas of the sky, near NGC 6888 the Crescent Nebula, it was not discovered until 2007 and cataloged in 2008. My goal for this image was to highlight and emphasize the nebula. It pushed my processing skills in PixInsight significantly. My strategy was to process the narrow band data as a bicolor image using 3 nights worth of data and diminish the stars significantly. I then combined a night's worth of short RGB exposures to restore the stars. The actual colors of the nebula are more artistic than they are scientific. I originally balanced the Ha and OIII data to reveal the nebula, but this caused the OIII to largely desaturate large parts of the the hydrogen clouds where there was significant OIII. To maintain the color of the hydrogen and also bring out the Soap Bubble, I selectively enhanced the contrast in the blue and green channels of just the Soap Bubble. The entire project was an exercise in making masks, as I used about a dozen of them for various purposes.

This image was taken from August 2 through August 5 at the 2018 Oregon Star Party. It is an RGBHaOIII image with 109x300sec Ha, 106x300sec OIII and 116x60sec, 105x60sec and 112x60sec red, green and blue respectively.

The equipment was an ASI1600MM-cool camera with Astrodon filters. The scope was an EdgeHD 8" with Celestron F/7 focal reducer on an Astro-Physics AP1600 mount with absolute encoders. Guiding was done via OAG with an Ultrastar camera. The narrow band exposures were done at gain 200 and offset 50, and the RGB exposures were done at gain 76 and offset 40.

Calibration, registration, statistical rejection and stacking were done in CCDStack. The remainder of the processing was done in PixInsight.

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Status	Advanced success
Started	...
Astrometry.net job	2209449
PixInsight job	4DFH1QQV97WCGZO8VNAY3YNMG1FFRC3R
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	20h15m19s.69
RA (top/left)	20h16m51s.80
RA (top/right)	20h13m47s.40
RA (bottom/right)	20h13m48s.96
RA (bottom/left)	20h16m51s.75

Dec (center)	+38°02′45″.8
Dec (top/left)	+38°16′47″.7
Dec (top/right)	+38°16′28″.4
Dec (bottom/right)	+37°48′39″.4
Dec (bottom/left)	+37°48′58″.5

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