M59-UCD3

M59-UCD3 is an ultra-compact dwarf galaxy located near the Messier 59 galaxy. As of 2015^[update], it is the second-densest galaxy currently observed, second to M85-HCC1.^[1][3]

M59-UCD3
Images of two ultracompact dwarf galaxies. M59-UCD3 is in the inset to the left, while M85-HCC1 is in the inset to the right.
Observation data (J2000 epoch)
Constellation	Virgo
Right ascension	12h 42m 11.041s[1]
Declination	+11° 38′ 41.21″[1]
Heliocentric radial velocity	373 ± 18[1]
Apparent magnitude (V)	16.34 ± 0.05[1]
Absolute magnitude (V)	−14.60 ± 0.09[1]
Characteristics
Mass	(1.8±0.3)×108[1] M☉
Half-light radius (physical)	20 ± 4 pc[1]
Other designations
SDSS J124211.04+113841.2[2]