The famous globular cluster Messier 13 (NGC 6205) in Hercules, seen in a BVR image composite with the 1-meter Jacobus Kapteyn Telescope (JKT) operated by the SARA consortium at La Palma. The nonlinear intensity mapping simultaneously shows stars with a wide brightness range, from the brightest red giants down to the main sequence.
For a wider view, here's a 10-minute red-light exposure taken with the UA 16-inch telescope. This spans a 17-arcminute field, giving a better impression of the large extent of the cluster.
Last changes: 9/2018 © 2001,2018