The Crescent Nebula lies about 2 degrees south of Sadr in the constellation of Cygnus, and is estimated to be approximately 5000 ly away. This rendition was taken on the night of 24th October with a Baader 7nm Ha filter, and is a result of stacking 9×15 minute exposures with a SX-VR H36 camera through a Pentax 75 telescope. Guiding was undertaken with an SX lodestar and SX-AO unit. Image was calibrated using Darks, bias, flats and dark flats. Stacking software was DSS.
The Crescent Nebula was 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 resulting in 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. The star at the centre of the Crescent Nebula sheds mass at a tremendous rate, close to a full solar mass in just 10,000 years.
Rework of the image after adding better calibration images, which has allowed the fainter nebulosity to be drawn out.
Thanks for looking, Steve