Messier 13 or M13, also designated NGC 6205 and sometimes called the Great Globular Cluster in Hercules or the Hercules Globular Cluster, is a globular cluster of several hundred thousand stars in the constellation of Hercules.
About 145 light-years in diameter, M13 is composed of several hundred thousand stars, the brightest of which is a red giant, the variable star V11, also known as V1554 Herculis, with an apparent visual magnitude of 11.95. M13 is 22,200–25,000 light-years away from Earth, and the globular cluster is one of over one hundred that orbit the center of the Milky Way.
M13 Hercules cluster
An early photograph of the Hercules cluster M13 with the CPC925 reflector telescope and Nikon D800 camera from Stuvsta in September 2015
M13 Hercules cluster
Photographed with APO107 refractor telescope and Nikon D800 camera in Stuvsta, September 2016.
5*60s exposure.
M13 Hercules cluster
Photographed with APO107 refractor telescope and Atik 360EX CCD monochrome CCD camera from Stuvsta in September 2019.
20min each LRGB filter
M13 Hercules cluster
Photographed with APO107 refractor telescope and Nikon D800 camera from Stuvsta in August 2020.
Exposure 55min.
M13 Hercules cluster
Photographed with APO107 refractor telescope and ASI 2600MC color camera from Stuvsta in August 2021.
8*3min exposure with IDAS LPS D2 light pollution filter.