Hercules Globular Cluster
June 23, 2012
Photographer: Greg Parker
Summary Author: Greg Parker
The image above shows the dazzling globular cluster M13 in the constellation of Hercules as observed from the New Forest Observatory in Hampshire, U.K. on May 24, 2012. Globular clusters are particularly dense nests of stars that tend to form in the halo around large galaxies. M13 or the Hercules Globular Cluster was discovered in 1714 by Edmond Halley. It contains several hundred thousand stars and is about 25,000 light years from the Sun -- it lies about the same distance from the galactic center. The Hercules Globular Cluster is one of the few globular clusters visible with the unaided eye from very dark locations, and with binoculars or a small telescope from most everywhere in the Northern Hemisphere from late spring through early fall. Note that the oblong smudge at upper right is the spiral galaxy NGC 6207.
Image details: Three hours of 10-minute sub-exposures (short exposures) with the Hyperstar III on my Celestron C11 telescope to facilitate deep sky viewing. Then we used one hour of one-minute sub-exposures and another hour of 50-second sub-exposures to regain the center of the core of M13 -- the 10-minute sub-exposures caused the core to saturate, so it just appeared white with no stars. All data taken by Professor Greg Parker at the New Forest Observatory and the image was processed by Noel Carboni in Florida, U.S.A.