NGC-6888 The Crescent Nebula
The Crescent Nebula Complex also known as NGC 6888, Caldwell 27, or Sharpless 105 is an emission nebula in the constellation Cygnus, about 5000 light-years away from Earth.
The Crescent Nebula is formed by the fast stellar wind from the Wolf-Rayet star WR 136 (HD 192163) colliding with and energizing the slower moving wind ejected by the star when it became a red giant around 250,000 to 400,000 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 (> 1 million degrees C) temperatures.
It is a rather faint object located about 2 degrees SW of bright star Sadr. For most telescopes visually 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”.
This is my 5 hour & 35 minute exposure, using my ZWO 174MM Camera HA + O3 + O3 data Combined with some QHY 183M HA Camera Data..both captured through my C6 F5 Newt. Scope with Coma Corrector.