Globular cluster
M10 (M10)
In Ophiuchus (Oph) • Magnitude 6.6 • 20 arcminutes
Open the free AstroPlanner with M10 pre-selected, scored against your telescope, location, and the live cloud forecast.
A bright, well-resolved globular cluster 14,300 light-years away in Ophiuchus. It forms a striking visual pair with M12 just 3° away in the sky, though in reality the two clusters are nearly 2,000 light-years apart from each other.
M10 at a glance
| Catalog IDs | M10, N 6254 |
| Type | Globular cluster |
| Constellation | Ophiuchus (Oph) |
| Right ascension | 16h 57m 07s |
| Declination | -04° 05' 60" |
| Apparent magnitude | 6.60 |
| Surface brightness | 11.7 mag/arcsec² |
| Angular size | 20.0 × 20.0 arcmin |
| Max altitude at 45°N | 41° |
| Best imaging months | Feb, Mar, Apr |
How to image M10
M10 sits in the constellation Ophiuchus at right ascension 16h 57m 07s and declination -04° 05' 60". 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.