Open cluster
Butterfly Cluster (M6)
In Scorpius (Sco) • Magnitude 4.2 • 25 arcminutes
Open the free AstroPlanner with Butterfly Cluster pre-selected, scored against your telescope, location, and the live cloud forecast.
A young star cluster whose brightest members trace a butterfly shape across the sky. Its standout star is BM Scorpii, a striking orange supergiant that marks the butterfly's head and varies unpredictably in brightness over weeks.
Butterfly Cluster at a glance
| Catalog IDs | M6, N 6405 |
| Type | Open cluster |
| Constellation | Scorpius (Sco) |
| Right ascension | 17h 40m 05s |
| Declination | -32° 15' 00" |
| Apparent magnitude | 4.20 |
| Angular size | 25.0 × 25.0 arcmin |
| Max altitude at 45°N | 13° |
| Best imaging months | Mar, Apr, May |
How to image Butterfly Cluster
Butterfly Cluster sits in the constellation Scorpius at right ascension 17h 40m 05s and declination -32° 15' 00". 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.