M3: a magnificent globular cluster
This is one of the brightest globular clustsers in the sky, barely visible even to the naked eye. From 32,000 light years its half a million stars appear as a faint glow in visual observation. The bright resolved stars are all giants; main sequence stars are all too faint to show up.
Images taken: May 1, 2006, by Ruth Mauldin and Jenzy Wunder.
Telescope: Meade 12 in with f/5.6 focal reducer (f=67in), guided on a 8.4 mg star.
Camera: SBIG ST-7 CCD
The arrows indicate RR Lyrae variables identified inside the cluster.
Seeing: 2.5 as.
Exposures: 20 min red, 20 min green, 2x20 min blue (1h20m total).
Images taken: on three nights in April 14-15, 2005, by Alexadra Rodriguez, Julia Taff, Jillien Fry, Thomas Kroger, and Edgar Ferguson.
Telescope: Meade 12 in with f/5.6 focal reducer (f=67in), guided on a 8.4 mg star.
Camera: SBIG ST-7 CCD
Seeing: 4 as.
Exposures: 1x15 min red, 2x15 min green, 4x15 min blue (1h45m total).
Image processing: CCDoops + CCDSoft + CCDsharp + Photoshop CS.