Silver Sliver Galaxy (NGC 891)
History
This galaxy was discovered, as is so often the case, by Wilhelm Herschel on 6 October 1784 with his 18.7 inch reflector telescope with a focal length of 20 feet. He entered it as V 19, the class «V» standing for very large nebulae. He described it as follows: «Considerabbly bright, much elongated, above 15' length 3' width, a black division of 3' or 4' length in the middle» [463] John L. E. Dreyer added the galaxy as NGC 891 in his «New General Catalogue of Nebulae and Clusters of Stars». [313] Because of its appearance, it has received the nickname «Silver Sliver» in the English-speaking world.
Physical Properties
We see the galaxy NGC 891 directly from the edge, similar to NGC 4565 in the constellation Coma Berenices. Noticeable is the dense band of dust in the middle. You think you are looking at a miniature version of our Milky Way. In fact, both galaxies are very similar both in appearance and size, which is particularly evident in the HST image in Fig. 2. The galaxy is of the type SA(s)b? Whereby the «b» for the opening of the spiral is uncertain due to the position of the edge. On Simbad one finds measurements for the speed from 528 km/s to 560 km/s and for the distance from 8.36 Mpc to 10 Mpc. [145]
| Designation | NGC 891 |
| Type | Gx (Sb) |
| Right Ascension | 02h 22m 33.0s |
| Declination | +42° 20' 50" |
| Diameter | 11.7 × 1.6 arcmin |
| Photographic (blue) magnitude | 10.8 mag |
| Visual magnitude | 9.9 mag |
| Surface brightness | 13.6 mag·arcmin-2 |
| Position Angle | 22° |
| Redshift | 0.001761 |
| Distance derived from z | 7.44 Mpc |
| Metric Distance | 10.200 Mpc |
| Dreyer Description | ! B, vL, vmE 22° |
| Identification, Remarks | UGC 1831, MCG 7-5-46, CGCG 538-52, IRAS 02195+4209 |
Finder Chart
The galaxy is located in the constellation Andromeda. Connect the two stars Almach (γ1 Andromedae) and Algol (β Persei). The galaxy is located about 3.5° from Almach on this line. NGC 891 is circumpolar, but is highest in the night sky from July to February.
Visual Observation
Description pending ...