Globular cluster
M54 (M54)
In Sagittarius (Sgr) • Magnitude 8.4 • 12 arcminutes
Open the free AstroPlanner with M54 pre-selected, scored against your telescope, location, and the live cloud forecast.
Though catalogued as a globular cluster, M54 actually belongs to the Sagittarius Dwarf Elliptical Galaxy — a small galaxy currently being torn apart and absorbed by the Milky Way. Sitting about 87,000 light-years away, it is literally the surviving core of a galaxy being cannibalized by our own.
M54 at a glance
| Catalog IDs | M54, N 6715 |
| Type | Globular cluster |
| Constellation | Sagittarius (Sgr) |
| Right ascension | 18h 55m 05s |
| Declination | -30° 28' 48" |
| Apparent magnitude | 8.37 |
| Surface brightness | 12.8 mag/arcsec² |
| Angular size | 12.0 × 12.0 arcmin |
| Max altitude at 45°N | 15° |
| Best imaging months | Mar, Apr, May |
How to image M54
M54 sits in the constellation Sagittarius at right ascension 18h 55m 05s and declination -30° 28' 48". To frame and integrate it well, AstroPlanner will compute the optimal moonless window for tonight from your location, the field-of-view fit against your sensor and focal length, the suggested total integration time given your aperture and sky Bortle class, and a cloud-aware schedule that drops it from the plan if your nearest cloud forecast spike overlaps the best altitude window.