The Andromeda Galaxy, also cataloged as Messier 31 and NGC 224, is a barred spiral galaxy that ranks among the most rewarding targets for astrophotographers of every skill level. Spanning an enormous 3.3° × 1.2° (200′ × 71′) on the sky, it comfortably overflows the field of view of many telescopes, making short focal lengths and wide-field refractors ideal for capturing its full, sweeping structure. At a bright apparent magnitude of 3.44 mag it reveals its glowing core quickly, yet its faint outer dust lanes and companion galaxies demand longer integration times and dark skies to record in full. A well-planned mosaic or a fast wide-field setup lets imagers bring out both the delicate spiral arms and the subtle color contrast between the golden bulge and the bluer star-forming regions.
Names and Catalog numbers
- Andromeda Galaxy
- M 31 (Messier 31)
- NGC 224
- UGC 454
- PGC 2557
Position and the cosmic neighborhood
The Andromeda Galaxy sits at right ascension 00h 42m 44.33s and declination +41° 16′ 07.5″ within its namesake constellation Andromeda, high in the autumn sky for northern observers. Its generous angular size of 3.3° × 1.2° makes it one of the few galaxies easily framed alongside its brighter companions, offering a natural composition for wide-field astrophotography. As the nearest large spiral to our own Milky Way at roughly 2.5 million light-years, it is a cornerstone of the Local Group and a favorite anchor for deep-sky imaging sessions. Its surface brightness of about 22.4 mag/arcsec² means the extended outer regions blend gently into the background sky, so careful exposure and gradient control are key to preserving its true extent.
Nice to Know
- Spanning about 148,000 light-years across, it is a physically massive spiral that dwarfs many of the galaxies commonly imaged from the backyard.
- Its bright magnitude of 3.44 mag makes it one of the most distant objects visible to the naked eye under dark skies, and an easy first galaxy to photograph.
- With a radial velocity of -300 km/s, it is actually approaching the Milky Way rather than receding, reflected in its negative redshift of z = -0.00100019.
- Its huge apparent size of 200′ × 71′ often requires a mosaic or a short focal length to capture in a single frame, a rarity among deep-sky targets.
Brightness, distance and size
The object has an apparent magnitude of 3.4 mag, it lies about 2.5 million light-years from Earth and spans roughly 148,000 light-years across. On the sky it appears about 3.3° × 1.2° (200′ × 71′) in size.
