M13 / NGC 6205 / Great Globular Cluster in Hercules
M13 was discovered by Edmond Halley in 1714, and cataloged by Charles Messier on June 1, 1764.
The Great Cluster in the constellation Hercules – also known as Messier 13, or M13 – is considered to be the finest globular cluster in the northern half of the heavens. It’s found in a star pattern called the Keystone – a lopsided square within the constellation Hercules – between the two brightest stars of northern spring and summer, Vega and Arcturus.
With an apparent magnitude of 5.8, it is barely visible with the naked eye on a very clear night. Its diameter is about 23 arc minutes and it is readily viewable in small telescopes. Nearby is NGC 6207, a 12th magnitude edge-on galaxy that lies 28 arc minutes directly north east.
M13 is about 145 light-years in diameter, and it is composed of several hundred thousand stars, the brightest of which is a red giant, the variable star V11, with an apparent visual magnitude of 11.95. M13 is 25,100 light-years away from Earth.
The Arecibo message of 1974, which contained encoded information about the human race, DNA, atomic numbers, Earth's position and other information, was beamed from the Arecibo Observatory radio telescope towards M13 as an experiment in contacting potential extraterrestrial civilizations in the cluster. While the cluster will move through space during the transit time, the proper motion is small enough that the cluster will only move 24 light years, only a fraction of the diameter of the cluster. Thus, the message will still arrive near the center of the cluster.
Camera Canon T2i modded
Exp. Time 40min. 24x100sec @ ISO1600
Midalnd, TX / May,2015
M13NGC6205Great Globular Cluster in HerculesFSQ106T2iFrancisco Herrera, from