Open cluster
NGC 581 (NGC581)
In Cassiopeia (Cas) • Magnitude 7.4 • 4.5 arcminutes
Open the free AstroPlanner with NGC 581 pre-selected, scored against your telescope, location, and the live cloud forecast.
NGC 581 is a open cluster located in the constellation Cassiopeia, at right ascension 01h 33m 22s and declination +60° 39' 29".
NGC 581 at a glance
| Catalog IDs | M103, N 581 |
| Type | Open cluster |
| Constellation | Cassiopeia (Cas) |
| Right ascension | 01h 33m 22s |
| Declination | +60° 39' 29" |
| Apparent magnitude | 7.40 |
| Angular size | 4.5 × 4.5 arcmin |
| Max altitude at 45°N | 74° |
| Best imaging months | Jul, Aug, Sep |
How to image NGC 581
NGC 581 sits in the constellation Cassiopeia at right ascension 01h 33m 22s and declination +60° 39' 29". 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.