| Object name: | Constellation: | Coordinates: | Apparent size: | Visual brightness: |
|---|---|---|---|---|
| NGC 772 | Aries | 01h59m / +19°00' | 7.2' x 4.3' | 10.3 mag |
The unbarred spiral galaxy NGC 772 (Arp 78) in the constellation Aries. The galaxy is around 200,000 light-years in diameter and is surrounded by several satellite galaxies - including the dwarf elliptical, NGC 770 - whose tidal forces on the larger galaxy have likely caused the emergence of a single elongated outer spiral arm that is much more developed than the other arms. Halton Arp includes NGC 772 together with NGC 770 in his Atlas of Peculiar Galaxies as Arp 78, where it is described as a "spiral galaxy with a small high-surface brightness companion". NGC 772 is about 130 million light-years from Earth and was discovered by Frederick William Herschel in 1785 (source: Wikipedia).
Fifty-six 3-minute exposures (167 minutes total exposure) at ISO 800 taken on October 26 / 27, 2019 and on November 21 / 22, 2020 were added for this shot with the DeepSkyStacker software and the final image processing was done in Photoshop.
Equipment: Canon EOS 450D Baader modified camera, TeleVue Paracorr Type II 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 equipment).
