The globular cluster M13 in Hercules is the finest visible from the northern hemisphere, rivaled only by M5 in Serpens.  It is located in western Her-cules, conveniently located along a line between two stars of the Keystone asterism of the constellation, ζ and η Herculis.  This view was obtained with a 135 mm lens and shows the high degree of concentration characteristic of it.  It is easily visible to the unaided eye in a dark sky since it glows at magnitude 5.8.  Unannotated view.