The Pinwheel Nebula (M99) in Coma Berenices
Images taken: March 29 and April 22, 2006, by Drew Mauldin, Winsor Yuan, Vincent Rotkiewicz, and Whitney Tarpy.
Telescope: Meade 12 in with f/5.6 focal reducer (f=67in), guided with an AO-7 adaptive optics accessory on a 6.5mg star.
Camera: SBIG ST-7 CCD
Exposures: 20 min in red, green, and clear; 3 images with 2900 sec total in blue (2 hours total), from a reasonably dark location 2 miles out of Oxford, at T=-20C.
Star size: 2.7 as; pixel size 1.09 as. Image size: 11 am x 8.5 am.
Image processing: CCDoops, CCDsoft + Photoshop CS.
The Pinwheel Nebula (not to be confused with the two Pinwheel Galaxies, M101 and M33), is also a spiral galaxy, but with one strnagely open arm. Observe the large number of HII regions glowing red along the spiral arms.