NGC 6888, The Crescent Nebula
NGC 6888, The Crescent Nebula, LBN203, Magnitude 10.0, Size 10.0' x 10.0', Constellation: Cygnus
Comments: The quoted magnitude value for this object, 10.0, is really a laugh. This is a very dim object; its actual surface brightness is a depressing 16. Surprisingly, it is actually quite doable visually from dark sites with scopes in the 11 - 12 inch aperture range--if they are equipped with an OIII or UHC filter. NGC 6888 is decidedly more challenging than the Veil Nebula. It is akin to it, however, in that it is more like a supernova remnant than a "normal" emission nebula. The Crescent appears to be made of the gas thrown off by a an evolved star near the center of its arc, a "Wolf-Rayet" star.
I was not sure whether the C8 and DSI would be up to the challenge of this dim semicircle of nebulosity, but they acquitted themselves very well, showing both detail in the nebula, and the very faint glowing gas on the inside of the arc.
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