At a Glance
Object: Messier 13
Type: Globular Cluster
Constellation: Hercules
Distance: 22,000 light-years
Catalog: Messier
Best Season: Summer
Messier 13, often called the Great Globular Cluster in Hercules, is one of the finest star clusters in the northern sky. Located in the constellation Hercules, this incredible ball of stars is a favorite target for both visual observers and astrophotographers.
M13 is a globular cluster, which means it is a tightly packed group of old stars held together by gravity. Unlike open clusters, which are usually younger and more loosely scattered, globular clusters are ancient stellar cities orbiting the outer halo of the Milky Way. M13 contains hundreds of thousands of stars, all crowded into a roughly spherical swarm.
The cluster is located about 22,000 light-years from Earth. Even at that distance, it is bright enough to be seen with binoculars under decent skies as a small fuzzy patch. Through a telescope, it begins to resolve into countless tiny points of light, especially around the outer edges.
M13 was first discovered by Edmond Halley in 1714. Charles Messier later added it to his famous catalog in 1764. Messier was searching for objects that could be mistaken for comets, and M13 became one of the most famous entries in his list.
One fun bit of history is that in 1974, a radio message known as the Arecibo Message was aimed toward M13. The cluster will have moved by the time the message reaches that region of space, but it remains a famous example of humanity trying to say hello to the universe.
For backyard astrophotography, M13 is a rewarding target because it is bright, detailed, and full of texture. A good image can show the dense glowing core along with individual stars sparkling around the edges, making it one of the best globular clusters to capture from a backyard sky.
Capture Details
| Telescope | Celestron Nexstar 8se |
| Reducer/Flattener | Celestron .63x Reducer/Flattener |
| Filter | Optolong L-Pro |
| Camera | ZWO ASI294 MC Pro |
| Mount | Skywatcher EQM-35 Pro |
| Total Captured | 69 |
| Total Time | 2 hours 42 minutes |
| Capture Software | N.I.N.A. |
Guiding | PHD2, ZWO asi120mm mini, |
| Processed in | PixInsight |
Backyard Capture Notes
M13 is a great backyard target because it is bright enough to capture well without extremely long exposure times. The main challenge is balancing the bright central core with the surrounding outer stars. If the core is stretched too aggressively, it can turn into a bright blob, but with careful processing, the cluster resolves into a beautiful swarm of individual stars. This is one of those objects where sharp focus, steady tracking, and good star color really make the final image stand out.