Photo of the Week for July 22, 2016
One of the summer sky’s undisputed highlights is M13, otherwise known as the Great Hercules Cluster. At magnitude 5.8, it can be perceived with the naked eye and is an easy binocular find. However, like all globular star clusters, M13 really comes into its own in a telescope. The object is impressive in small apertures, but the increased resolution of bigger instruments show the cluster to even greater effect. In a large backyard scope, M13 is a spectacular swarm of luminous pinpoints. This portrait by Martin Bernier of Saint-Liboire, Québec, nicely conveys the famous globular’s telescopic appearance. Uncountable stars are arrayed across the field of view, including the cluster’s densely-packed core.
Martin captured this photo with a QSI 683wsg-8 cooled CCD camera attached to an Astro-Tech AT12IN 12-inch f/4 imaging Newtonian reflector telescope. The final image combines 145 minutes total exposure shot through four different filters.