[2] About one third of the way from Vega to Arcturus, four bright stars in Hercules form the Keystone asterism, the broad torso of the hero.

With an apparent magnitude of 5.8,[2] Messier 13 may be visible to the naked eye with averted vision on dark nights.

[11] At least four inches of telescope aperture resolves stars in Messier 13's outer extent as small pinpoints of light.

[14] A small galaxy, IC 4617, lies halfway between NGC 6207 and M13, north-northeast of the large globular cluster's center.

The 1974 Arecibo message, 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 Messier 13 as an experiment in contacting potential extraterrestrial civilizations in the cluster.