ngc6888 (Crescent Nebula) bi-colour


Chris Heapy

Macclesfield, UK

Scope: Televue NP127is
CCD: Atik490EX
Mount: Losmandy G11
Guide: TV Pronto + Lodestar
25 x 1200s subframes

All image data aquired from my back garden in Macclesfield, UK.

ngc6888 (The Crescent Nebula) is an emission nebula located about 5000 lightyears away in the centre of constellation of Cygnus the Swan. It 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. 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.

This is image is a bi-colour composite (H-alpha and OxygenIII) and the challenge was to reveal the delicate OIII shell which gives the appearance of dressing the emission nebula in a blue negligee :-) Overall, the object has a large dynamic range which demands HDR techniques to reveal all parts without burning out the highlights.