Open cluster
M37 (M37)
In Auriga (Aur) • Magnitude 6.2 • 24 arcminutes
Open the free AstroPlanner with M37 pre-selected, scored against your telescope, location, and the live cloud forecast.
The richest of the three Auriga Messier clusters, containing about 500 stars including numerous red giants. The abundance of cool orange giant stars reflects its age of about 300 million years — old enough for the cluster's most massive members to have swelled into giants at the end of their lives.
M37 at a glance
| Catalog IDs | M37, N 2099 |
| Type | Open cluster |
| Constellation | Auriga (Aur) |
| Right ascension | 05h 52m 23s |
| Declination | +32° 32' 60" |
| Apparent magnitude | 6.20 |
| Angular size | 24.0 × 24.0 arcmin |
| Max altitude at 45°N | 78° |
| Best imaging months | Sep, Oct, Nov |
How to image M37
M37 sits in the constellation Auriga at right ascension 05h 52m 23s and declination +32° 32' 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.