NGC 7331 (Pegasus)
Fig. 1 - Similar in size, shape, and mass to the Milky Way: The unbarred spiral galaxy NGC 7331 in Pegasus, photographed with a 16-inch f/4.5 Dob on an equatorial platform.
| Object name: | Constellation: | Coordinates: | Apparent size: | Visual brightness: |
|---|---|---|---|---|
| NGC 7331 | Pegasus | 22h37m / +34°25' | 10.5' x 3.7' | 10.4 mag |
The unbarred spiral galaxy NGC 7331 (Caldwell 30) in the constellation Pegasus. The galaxy is about 40 million light-years from Earth and was discovered by the British-German astronomer William Herschel in 1784. More galaxies can be seen above and around NGC 7331. The galaxies directly above NGC 7331 are NGC 7340, NGC 7337, NGC 7335, NGC 7336 (for more details see labeled image below). They are 300-400 million light-years from Earth (source: Wikipedia).
The galaxy appears similar in size and structure to the Milky Way, and is sometimes referred to as "the Milky Way's twin". However, discoveries in the 2000s regarding the structure of the Milky Way may call this similarity into doubt, particularly because the latter is now believed to be a barred spiral, compared to the unbarred status of NGC 7331. In spiral galaxies the central bulge typically co-rotates with the disk but the bulge in the galaxy NGC 7331 is rotating in the opposite direction to the rest of the disk.
Exposure time: 2h 31min (46x approx. 3min) at ISO 800, taken on August 4, 2016 and on August 8, 2016. Processing with Deep Sky Stacker and Photoshop. No calibration frames were taken.
Equipment: Canon EOS 450D Baader modified camera, TeleVue Universal Paracorr coma corrector, 16" f/4.5 "Ninja" dobsonian telescope riding on a dual-axis Tom Osypowski equatorial platform, Lacerta MGEN autoguider, Lacerta off axis system.
Field of view comparison: image of the moon with the same setup.
Fig. 2 - Labeled image of NGC 7331.
Fig. 3 - Search chart for NGC 7331. Copyright 2025 'The Mag-7 Star Atlas Project', www.siaris.net.