NGC 818

NGC 818 is an intermediate spiral galaxy in the constellation of Andromeda. Its velocity with respect to the cosmic microwave background is 4,010±17 km/s, which corresponds to a Hubble distance of 192.9 ± 13.5 Mly (59.14 ± 4.15 Mpc).^[1] Additionally, 14 non-redshift measurements give a closer mean distance of 168.62 ± 8.37 Mly (51.700 ± 2.565 Mpc).^[2] It was discovered by German-British astronomer William Herschel on 18 October 1786.^[3][4]

NGC 818
NGC 818 imaged by Pan-STARRS
Observation data (J2000 epoch)
Constellation	Andromeda
Right ascension	02h 08m 44.5464s[1]
Declination	+38° 46′ 37.596″[1]
Redshift	0.014156±0.0000130[1]
Heliocentric radial velocity	4,244±4 km/s[1]
Distance	168.62 ± 8.37 Mly (51.700 ± 2.565 Mpc)[1]
Group or cluster	[CHM2007] LDC 148
Apparent magnitude (V)	13.20[1]
Characteristics
Type	SABc[1]
Size	~171,700 ly (52.64 kpc) (estimated)[1]
Apparent size (V)	3.0′ × 1.3′[1]
Other designations
IRAS 02057+3832, 2MASX J02084451+3846381, UGC 1633, MCG +06-05-086, PGC 8185, CGCG 522-116[1]

NGC 818 has a possible active galactic nucleus, i.e. it has a compact region at the center of a galaxy that emits a significant amount of energy across the electromagnetic spectrum, with characteristics indicating that this luminosity is not produced by the stars.^[5][6]

Galaxy group

NGC 818 is a member of a galaxy group known as [CHM2007] LDC 148. The other galaxies in the group are NGC 834, NGC 841, NGC 845, UGC 1673, and UGC 1721.^[7][8]

Supermassive black hole

According to a paper based on measurements of the near-infrared K-band luminosity of the galaxy's bulge, NGC 818 has a supermassive black hole with a mass of 1×10^7.1M_☉ (13 million solar masses).^[9]

Supernova

One supernova has been observed in NGC 818:

• SN 1992az (Type II, mag. 18) was discovered by Christian Pollas on 27 September 1992.^[10][11]

See also

• List of NGC objects (1–1000)