Hercules

In James Blish's Cities In Flight, the Web of Hercules, controlling matter-anti-matter interactions, succeeds the Earthman culture as the fourth great civilization in the Milky Way.

In Blish's The Quincunx Of Time, Earth Security has a Hercules Station. See here.

In Poul Anderson's Planet Of No Return, an expedition of astronomers explores Hercules: a dense cluster of millions of Population II stars in singularly clear space. Within the cluster, the double star, Lagrange, has a double planet, the larger remarkably terrestroid. Closer exploration is necessary.