Messier 4
Binoculars • Globular Clusters
Image: ESO Imaging Survey
Finder map for Messier 4
A classic and popular object for amateur astronomers due to its brightness, size, and ease of location. It serves as a textbook example of a globular cluster for public outreach and education. Difficult for far northern latitudes as it does not rise high above the southern horizon. Best viewed from mid-northern to southern latitudes. Noticing the cluster’s uneven or slightly elongated core and separating its faint outer halo from the rich Milky Way star field. Fully resolving the distinctive central bar of stars becomes easier with small to moderate telescopes under steady seeing.
Finder scope & binocular view of Messier 4
| Property | Value |
|---|---|
| Common names | M4 |
| Catalog names | M 4, NGC 6121, Mel 144 |
| Type | Stellar Cluster |
| Subtype | Globular Cluster |
| Coordinates | 16h 23m 35.22s, -26° 31’ 32.70” |
| Season | May - July |
| Best month | June |
| Beginner friendly | Marginal |
| Visual reward | Moderate |
| Filters required | None |
| LP tolerance | High |
| Minimum equipment | Naked eye |
| Optimal equipment | Small telescope |
| Magnitude | 5.4 |
| Size | 36.0 arcminutes x 36.0 arcminutes |
| Constellation | Scorpius |
Observation Notes
Naked Eye
Marginally detectable to experienced observers under exceptionally dark and transparent skies (typically Bortle 1–2) as a faint, fuzzy patch very close to the bright star Antares. Averted vision is usually required, and visibility is strongly affected by sky conditions and glare.
Binoculars
Easily visible as a moderately large, round, hazy glow with a loose appearance. Clearly non-stellar, though individual stars are not resolved.
Small Telescope
Begins to resolve at the edges, showing a noticeable salt-and-pepper texture. The cluster appears large and loosely concentrated, with a relatively open structure.
Medium Telescope
Resolves into large numbers of faint stars across much of the cluster. The distinctive central bar of brighter stars—one of M4’s defining features—can be detected under good seeing and appropriate magnification.
Large Telescope
Reveals extremely rich star resolution and pronounced granularity throughout most of the cluster. Numerous star chains and uneven density patterns are visible, while the innermost core remains densely packed and only partially resolved rather than fully broken into individual stars.