Globular cluster
M30 (M30)
In Capricornus (Cap) • Magnitude 7.7 • 12 arcminutes
Open the free AstroPlanner with M30 pre-selected, scored against your telescope, location, and the live cloud forecast.
A moderately bright globular cluster in Capricornus that has undergone "core collapse" — a catastrophic gravitational compression of its centre, the same dramatic process seen in M15. This runaway implosion is triggered when the most massive stars sink inward and release gravitational energy over billions of years.
M30 at a glance
| Catalog IDs | M30, N 7099 |
| Type | Globular cluster |
| Constellation | Capricornus (Cap) |
| Right ascension | 21h 40m 23s |
| Declination | -23° 10' 48" |
| Apparent magnitude | 7.70 |
| Surface brightness | 12.3 mag/arcsec² |
| Angular size | 12.0 × 12.0 arcmin |
| Max altitude at 45°N | 22° |
| Best imaging months | May, Jun, Jul |
How to image M30
M30 sits in the constellation Capricornus at right ascension 21h 40m 23s and declination -23° 10' 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.