Crescent Nebula (NGC 6888) and "Soap Bubble" Nebula (PN G75.5+1.7)

Crescent and Bubble
All Images Copyright Steve Cannistra

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RA: 20h 13m 28s (J2000)
Dec: +38 degrees 15' 12" (J2000)

The Crescent Nebula in the upper right portion of this image (NGC 6888) is the result of a dying central Wolf-Rayet star (WR 136) that is shedding massive amounts of gas and UV irradiation, the latter exciting hydrogen and oxygen to emit in the red and blue wavelength ranges, respectively.  It's estimated that the central Wolf-Rayet star responsible for forming the Crescent Nebula will go supernova within the next 100,000 years.  The "Soap Bubble" nebula (PN G75.5+1.7), located in the lower left portion of the image, is a planetary nebula recently discovered by amateur astronomer Dave Jurasevich on July 5, 2008.  It is well worth reading Dave's account of this discovery, which also shows some of the original data that reveals how faint this object is.  It took a lot of work for me to dig this nebula out of the background, but it was well worth the effort.  More information on NGC 6888 may be found on Rob Gendler's webpage.

Photographic Details:
Dates:  August 19, 20, 21, 2017
Scope:  Takahashi FSQ106 at f5 on the Takahashi NJP Mount
Autoguider:  SBIG ST-402 with 60mm guidescope, focal length 227mm
Camera:  Starlight XPress SX814 CCD camera at -20C, resulting in an image scale of 1.44 arcsec/pixel with the FSQ106
Filters:  Baader Ha, OIII, RGB
Exposures:  Total exposure 16 hours
Post-processing:  Calibrated, aligned and stacked in Maxim, followed by DDP in ImagesPlus (IP).  Further processing in Photoshop CS (16 bit format)

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