M13, The Great Hercules Cluster, is one of the most magnificent objects visible from mid-northern latitudes. This globular cluster is a naked eye object positioned about two-thirds the way from Zeta to Eta Herculis. Four stars form a keystone asterism in Hercules. Although not among the most brilliant stars of the summer sky, the keystone is readily available to the naked eye from a typical rural observing site. A line from Deneb through a point just north of Vega will point the way to the keystone. Eta and Zeta Herculis form one of the long legs in the keystone asterism. M13 resides along a line between these stars, about two-thirds the way from Zeta to Eta.
| Summer Sky Tour: M13-The Great Hercules Cluster (Hercules) RA: 16h 41.7m / DEC: +36° 27'.6 |
|
|
Home | About Cosmic Voyage | Getting Started | Deep-sky Observing | Planetary Observing | Astrophotography | Sketching | Glossary | Web Links
URL: http://www.cosmicvoyage.net
Layout, design & revisions © W. D. Ferris
Comments and Suggestions: wdferris1@gmail.com
Revised: February 4, 2002 [WDF]
The view through moderate aperture is simply stunning. My 10-inch shows a very concentrated 20' diameter cluster with stars resolved to the center. The best observing conditions reveal tendrils of stars reaching out from the core of this 5.8 magnitude beauty. At times, M13 reminds me of a celestial octopus. The cluster is flanked by a 6.9 magnitude star 15' to the east and a 7.3 magnitude star 18' to the southwest. If you look about 26' northeast of M13, you may see the 11.7 magnitude galaxy,