Galaxy
Triangulum Galaxy (M33)
In Triangulum (Tri) • Magnitude 5.7 • 1.2 degrees
Open the free AstroPlanner with Triangulum Galaxy pre-selected, scored against your telescope, location, and the live cloud forecast.
The third-largest member of our Local Group of galaxies, and one of the most distant objects ever spotted (barely) with the naked eye under exceptional dark skies. Despite being only 2.7 million light-years away, its light is so spread out it is notoriously hard to see. It contains the largest known stellar nursery in the Local Group: NGC 604, a region 1,500 light-years wide where hundreds of massive stars are being born simultaneously.
Triangulum Galaxy at a glance
| Catalog IDs | M33, N 598 |
| Type | Galaxy |
| Constellation | Triangulum (Tri) |
| Right ascension | 01h 33m 54s |
| Declination | +30° 39' 36" |
| Apparent magnitude | 5.72 |
| Surface brightness | 14.2 mag/arcsec² |
| Angular size | 73.0 × 45.0 arcmin |
| Max altitude at 45°N | 76° |
| Best imaging months | Jul, Aug, Sep |
How to image Triangulum Galaxy
Triangulum Galaxy sits in the constellation Triangulum at right ascension 01h 33m 54s and declination +30° 39' 36". 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. As a galaxy, Triangulum Galaxy needs the darkest skies you can find: surface brightness, not just apparent magnitude, drives whether it will lift out of the gradient.