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Sagittarius Dwarf Galaxy

Sagittarius Dwarf Spheroidal Galaxy, Sgr dSph, Sgr DEG

Proper NamesSagittarius Dwarf Galaxy (abbreviated to Sgr dSph, Sgr DEG)
Messier NumberNone
NGC/IC NumberNone
Other DesignationsPGC 4689212
ConstellationSagittarius
Right Ascension18h 55m 3s
Declination-30° 28' 42"
Distancec.65,200 light years
c.20,000 parsecs
MagnitudeApparent: +4.5
Absolute: -11.2
Mean DiameterApparent: 7° 30'
Actual: c.6,000 light years
Hubble TypeE-S0 Elliptical/Lenticular
Optimum VisibilityJuly
NotesThis dwarf galaxy is known in full as the Sagittarius Dwarf Spheroidal Galaxy (or Dwarf Elliptical Galaxy), to avoid confusion with the Sagittarius Dwarf Irregular Galaxy, another much more distant dwarf galaxy that lies somewhat to the north within Sagittarius.

The Sagittarius Dwarf Galaxy is not directly visible in normal light, but this image shows the approximate region of the sky that it would occupy if it could be seen. The central object here is the globular cluster M54, which is thought to be a satellite cluster of the dwarf galaxy. The bright foreground star to the east (left) is Ascella or Zeta Sagittarii. Imagery provided by Aladin sky atlas

One of a number of small galaxies known to be associated with the Milky Way spiral. The Sagittarius Dwarf Galaxy is roughly spheroid in shape, approximately six thousand light years in diameter. It is unusual in that appears to be in to process of 'colliding' with our own Galaxy. This event is taking place at the base of the Outer Arm, on the other side of the Galaxy from our Sun.

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