The Sagittarius Dwarf Elliptical Galaxy.
Discovered in 1994 by R. Ibata, M. Irwin and G. Gilmore by looking at the brightness and density of stars. At 80,000 light years, it was immediately recognized as being the nearest known neighbor to the Milky Way, much closer than the Large Magellanic Cloud (179,000 light years)
which was previously considered to be our closest companion. This title however was taken in 2003 by Canis Major Dwarf which is now the closest companion galaxy to our own Milky Way.
This should not be confused with SagDIG (Sagittarius Dwarf Irregular Galaxy) which was formerly known as Sagittarius I Dwarf which leads to ambiguous references.
SagDEG is one of the most recently discovered members of the
Local Group and is currently being consumed by the Milky Way. It is currently in the process of being disrupted by tidal gravitational forces. It is believed that there is a large amount of dark matter within SagDEG holding it together.
Right Ascension: 18:55.1 (h:m)
Declination: -30:29 (deg:m)
Distance: 80.0 (kly)
Apparent Dimension: 190x490 (arc min) (5x10 degrees)