Took this with a Lunt100MT but wasn't paying attention to detail and had the backfocus all wrong, so I had to crop it. I swear my Lunt100MT is cursed for dark work. The
Crescent Nebula (also known as
NGC 6888,
Caldwell 27,
Sharpless 105) is an
emission nebula in the constellation
Cygnus, about 5000
light-years away from
Earth. It was discovered by
William Herschel in 1792.
[2] It is formed by the fast
stellar wind from the
Wolf-Rayet starWR 136 (HD 192163) colliding with and energizing the slower moving wind ejected by the star when it became a
red giant around 250,000
[3] to 400,000[
citation needed] years ago. The result of the collision is a shell and two
shock waves, one moving outward and one moving inward. The inward moving shock wave heats the stellar wind to
X-ray-emitting temperatures.It is a rather faint object located about 2 degrees SW of
Sadr. For most telescopes it requires a
UHC or OIII filter to see. Under favorable circumstances a telescope as small as 8 cm (with filter) can see its nebulosity. Larger telescopes (20 cm or more) reveal the crescent or a
Euro sign shape which makes some to call it the "Euro sign nebula".
Comments