NGC 6888 - Crescent Nebula HOO (2019) & Soap Bubble

Thanks to Luca Marinelli for pointing out the Soap Bubble Nebula (PN G75.5+1.7) on right side.

The Crescent Nebula (NGC 6888) is a massive bubble 25 light-years across and approximately 5000 light-years away in the constellation Cygnus.  This object is the result of the collision of faster moving stellar wind from a Wolf-Rayet star (a star that lost its outer hydrogen layer) colliding with and energizing slower moving wind ejected by the star when it became a red giant sometime around 250,000 to 400,000 years ago.  The star known as WR136 is near the end of its stellar life and will probably go out in a supernova most likely not in our lifetime though.  It is the bright yellowish star near the center of the Crescent.  

I captured this object almost exactly two years ago with my old setup and using a UHC filter.  For what I had it was OK but I really wanted to capture the blue-green hue of the oxygen mingling with the red hydrogen I had to wait until now.  I obtained about 3 hours of Ha and 5 hours of OIII to ensure there was enough to produce the HOO image.  I thought I was going to crop it more but I really liked the nebulosity so I kept it wide field.  Additionally, I reduced the stars a bit more than I usually do because I wanted to highlight the surrounding nebulosity especially in the lower left where they almost look like wave fronts.  Lastly, after many test adjustments, I did not darken the background too much liked the faint red-blue hue of the surrounding nebulosity.

Video

Image

NGC 6888 - Crescent Nebula

Home Monroe, CT
Date: 7-13-19, 7-14-19, 7-30-19, 8-9-19, 8-11-19
Camera: ZWO ASI1600MM-Pro
Telescope: Astro-Tech AT115EDT 115mm Refractor Telescope
Barlow: None
Focal Length: 805mm
f/7
Focal Reducer: Astro-Tech 0.8x Focal Reducer/Field Flattener for Refractor Telescopes
Mount: Orion Atlas Pro
Filter Wheel: ZWO EFW 8x 1.25"
Filter: ZWO Ha, OIII
Focuser: ZWO EAF
Autoguiding: QHY-5L-II-M attached to an Agena 50mm Guide Scope with Helical Focuser
Exposure: Ha 59 x 180s, OIII 97 x 180s

Gain: 139
Offset 21
Temp: 17 C
Post Processing: PixInsight, Photoshop
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