NGC 185 (also known as Caldwell 18) is a dwarf spheroidal galaxy located in the southern part of Cassiopeia. It's about 2 Million light years distant and like neighbouring dwarf galaxy NGC 147 (Caldwell 17) is a satellite of the Andromeda galaxy (M31) and a member of the Local group. It shines at mag. +9.1 and since brighter, smaller and more compact than its neighbour is easier to spot.
Dwarf spheroidal galaxies are similar to dwarf elliptical galaxies only that they are approximately spheroidal in shape, generally of a lower luminosity and recognised only as satellite galaxies in the Local Group. They are also believed to contain large amounts of dark matter.
NGC 185 was discovered by William Herschel on November 30, 1787 and was first photographed between 1898 and 1900 by James Edward Keeler using the 36-inch (910 mm) "Crossley Reflector" telescope at the Lick Observatory in California, USA.
For a dwarf galaxy, NGC 185 has some interesting characteristics including an active galactic nucleus (AGN). It's sometimes classified as a type 2 Seyfert galaxy although this is debatable but if correct, it would mean it's the closest Seyfert galaxy to Earth and the only known Seyfert in the Local Group. The majority of galactic star formation took place in early times.
A starting point for locating NGC 185 is bright star Schedar (α Cas - mag. +2.2) in the "W" of Cassiopeia. An imaginary line extending 8 degrees southwards from Schedar takes you to almost exactly where the galaxy is located. The star omicron Cas (ο Cas - mag. +4.5) is a degree east of NGC 185 with NGC 147 a degree on the western side.
NGC 185 is within the range of small and medium size scopes. It has an apparent size of 11.4 x 10.0 arc minutes, although visually appears much smaller. Through an 80mm (3.1-inch) refractor the galaxy is fairly simple to spot in dark skies and considerably easier than NGC 147. It appears as a small faint hazy oval of light spanning about 2 to 3 arc minutes with no obvious sharp centre. With larger scopes of the order of 200mm (8-inch) or greater, the galaxy appears more defined and slightly brighter, especially towards the middle. On good nights it may even be possible to notice finer details such as mottling.
NGC 185 is best seen from the Northern Hemisphere latitudes during the months of October, November and December.
NGC 185 Data Table
|Object Type||Dwarf Spheroidal Galaxy|
|Distance (ly)||2.0 Million|
|RA (J2000)||00h 38m 58s|
|DEC (J2000)||48d 20m 27s|
|Apparent Size (arc mins)||11.4 x 10.0|
|Notable Feature||Satellite galaxy of the Andromeda Galaxy (M31)|