Galactic Anti-Centre

If we use the galactic coordinate system to locate objects within the Galaxy, we can identify the galactic anti-centre as the point where the galactic longitude ( l ) = 180 degrees and the galactic latitude ( b ) = 0 degrees.

The galactic coordinate system. Positions of objects are measured in terms of their galactic longitude ( l ) and galactic latitude ( b ). The galactic equator slices the galaxy in half (top and bottom).

The galactic anti-centre is directly opposite the galactic centre, so the number density of stars decreases as we are looking towards the outer edge of the Milky Way. It is located in the constellation Gemini, with celestial coordinates (epoch J2000.0):

RA = 6h 17m 0.0s Dec = +22d 30m 0.0s

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