anticenter

Anticenter is the direction in the sky opposite the Galactic Center within the Milky Way's coordinate system. In galactic coordinates, anticenter is defined by longitude l = 180 degrees and latitude b = 0 degrees, pointing outward from the center along the galactic plane. In equatorial coordinates, this direction is near right ascension about 5h45m and declination about +29 degrees, lying in the constellation Auriga.

Because the anticenter points away from the crowded central regions, it is a common region for surveys of the Milky Way's outer disk and halo. It has been used to study stellar populations, kinematics, and chemical abundances in the outer disk, as well as halo substructures such as stellar streams and rings, including the Anticenter Stream and the Monoceros Ring.

Observationally, the anticenter region presents both challenges and advantages: there is lower extinction than in some directions toward the plane, but the line of sight intersects multiple Galactic components, making interpretation of velocity and metallicity data complex. Large surveys such as SDSS, Gaia, and APOGEE have mapped this region to characterize its structure and formation history.

See also Galactic center, Galactic coordinate system, galactic longitude, Anticenter Stream, Monoceros Ring, Milky Way structure.