Messier 71 is a compact but relatively loose globular cluster that was long mistaken for a dense open cluster due to its appearance and stellar composition. Discovered by Philippe Loys de Chéseaux before 1746 and catalogued by Charles Messier in 1780, it is located in the rich star fields of the Milky Way, making it a beautiful and rewarding target for astrophotographers. Its stars are moderately resolved even in small telescopes, and deep images reveal a subtle, grainy texture with a golden hue. The cluster’s lack of a dense core and its rich background of Milky Way stars make it stand out in wide-field astrophotography.
Names and Catalog numbers
- Messier 71
- M71
- NGC 6838
- Melotte 226
Position and the cosmic neighborhood
Messier 71 is located in the small constellation Sagitta, the Arrow, almost exactly halfway between the bright stars Gamma Sagittae and Delta Sagittae. The cluster lies in a dense region of the Milky Way, surrounded by rich star fields and faint dark nebulae, providing a dramatic backdrop for astrophotography. M71 is also near the famous “Coathanger” asterism (Collinder 399), making it easy to locate and an attractive addition to wide-field images. The area is relatively free of bright foreground stars, allowing the cluster’s structure to be clearly captured in images.
Nice to Know
- Messier 71 was considered an open cluster for many years until its true nature as a globular cluster was confirmed in the 1970s.
- The cluster is relatively metal-rich compared to most globular clusters, giving its stars a slightly warmer hue.
- M71 lacks a dense core, making it appear more diffuse and less concentrated than typical globular clusters.
- Astrophotographers value M71 for its unique appearance and the rich Milky Way background in which it is embedded.
Brightnes, distance and size
Messier 71 has an apparent magnitude of about 6.1, making it visible in binoculars and small telescopes under dark skies. The cluster is approximately 12,000 to 13,000 light-years away from Earth and spans about 27 light-years in diameter. Its apparent size is roughly 7 arcminutes, about a quarter of the apparent diameter of the full Moon, making it a compact but striking target for astrophotography, especially in wide-field images.
