2014/07/17 - Fourth light of our remote setup. This time a nice narrowband object, The Crescent Nebula. This image is a combination of 6 channels; Hydrogen-alpha, Oxygen-III, Sulfur-II and RGB for correct star color. We spent 35 hours on this object, that's our record for now. Seeing fluctuated during the 8 days we images this object, it was between 2" and 5".
The Crescent Nebula is an emission nebula in the constellation Cygnus, about 5000 light years away. 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 around 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 temperatures.
35 hours total exposure time
12x 300 sec. RGB unbinned for star color
21x 1800 sec. hydrogen-α unbinned
24x 1800 sec. oxygen-III unbinned
19x 1800 sec. sulfur-II unbinned
Image acquisition with ACP Observatory Control Software, ACP Scheduler and Maxim DL
Auto-guiding with Maxim DL
Auto-focusing with FocusMax
