The Bubble Nebula is a hydrogen-rich emission nebula in the constellation Cassiopeia. It is 11,000 light years from Earth. This photo also includes the open cluster M52 and NGC7538.

This image is a composite of shots from two sessions.  The area immediately around the bubble is from my AP 142 at f/7.5 (1065mm focal length), while the rest of it was done with the AT111EDT at f/5.6 (622mm fl).

The wide shot was the first image I captured with my Astro-Physics Mach1GTO mount. Captured on 2011-10-25 & 26 at Wa-chur-ed Observatory using H-alpha for red plus green and blue filters. The bubble area was captured with H-alpha and OIII filters.

This is a great target. In addition to the unique look of the bubble, there are interesting areas all around it that can make for a good composition at many different focal lengths.

Scope: AT111EDT at f/5.6 & AP 142 at f/7.5
Mount: AP Mach1GTO
Camera: QSI 583 at –25C
Exposure (wide): 12 x 900s H-a, 20 x120s G, 17 x 120s B (4 hrs 14 mins total)
Exposure (bubble): 6 x 900s H-a, 4 x 900s OIII (2 hrs 30 mins total)