This is an image of the globular cluster M13 taken with a 2048 pixel by 2048 pixel CCD on the 0.9m telescope at the Kitt Peak National Observatory. The image was taken through a V filter, which corresponds to green light. With an absolute magnitude of -8.50, it contains about a million stars.
Globular clusters are the oldest, densest, and most populous star clusters in our galaxy.
This image was taken to support spectroscopic searches for binary stars in the cluster.