ESO 306-17

ESO 306-17 is a fossil group giant elliptical galaxy in the Columba constellation, about 1.07 million light-years in diameter,[2][4] and roughly 517 million light-years away.[2]

ESO 306-17
Image of ESO 306-17 by the Hubble Space Telescope Release date: 4 March 2010
Observation data (J2000.0 epoch)
Constellation	Columba
Right ascension	05h 40m 06.73s[1]
Declination	−40° 50′ 10.6″[1]
Redshift	0.035805±0.000083[2]
Heliocentric radial velocity	10,734±25 km/s[2]
Galactocentric velocity	10,544±26 km/s[2]
Distance	517.3 ± 36.20 Mly (158.6 ± 11.1 Mpc)h−1 0.6774 (Comoving)[2] 506 Mly (155.1 Mpc)h−1 0.6774 (Light-travel)
Apparent magnitude (B)	13.36[1]
Characteristics
Type	E+3[2]
Size	1,070,000 ly × 706,100 ly (328.04 kpc × 216.50 kpc) (diameter; 90% total B-band light)[2][lower-alpha 1] 399,300 ly × 287,500 ly (122.42 kpc × 88.15 kpc) (diameter; "total" magnitude)[2][lower-alpha 1]
Apparent size (V)	2.5′ × 1.5′ (V-band)[2]
Other designations
MCG -07-12-009, PGC 17570[3]

The galaxy is situated alone in a volume of space about it. It is theorized that the galaxy cannibalized its nearest companions, hence, being a fossil group.[5] The galaxy is a giant elliptical of type cD3[2] (E+3), one of the largest types of galaxies.