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NGC 6888 is, in many ways, an unusual nebula. It is the result of the evolution of its central star HD 192163 (also known as WR 136, because it is a Wolf Rayet star). It started (about 5 Million years ago) as a supergiant O star, with a mass higher than 30 solar masses. Short ago (cosmologically speaking…) it became a red supergiant. It was shedding layers at a tremendous speed. It then reached its current phase: Wolf Rayet star. This star will end its days exploding as a supernova, about 100,000 years in the future. The strong stellar winds have shaped this nebula, and the radiation shock waves have excited it to emit in the two most common emission lines: Halpha and OIII.
This image has a special meaning to me, because it is the first image that I have been able to take within the scope of a new telescope partnership (additional to the currently existing one with Don Goldman with his telescopes located in Australia). Since a few months ago, I became telescope partner of the Blackbird II Observatory, belonging to Jay GaBany (also one of the big gurus in Astrophotography), located in the Sierra Nevada, California. Now, I can also get images of objects located in the Northern Hemisphere. I am very grateful to Jay for giving me this opportunity.
Name(s): NGC 6888. Caldwell 27. Crescent Nebula.
Type: Emission Nebula
RA: 20h 12m 29.6s
Dec: +38º 25’ 02”
Size (arcmin): 25×14
Distance: 5,400 ly
Date: 2018-04-24 to 2018-08-31
Location: Sierra Remote Observatory (SRO) near Alder Springs, CA, USA
Size (arcmin): 31×31
Telescope: Officina Stellare RC500 Pro (20” f/8)
Camera: Apogee Alta U16M-HC (4096x4096pix)
Guiding: Astrodon MonsterMOAG off-axis guider
Total exposure: 17.5 hours (Ha: 560min=14x40min; OIII: 400min=10x40min; RGB: 1h 35m)
Processing: CCDStack, Photoshop CC 2018