Vol 15, No 7

Galactic coordinate system based on multi-wavelength catalogs

Ping-Jie Ding, Zi Zhu, Jia-Cheng Liu


Abstract The currently used Galactic coordinate system (GalCS) is based on the FK5 system at J2000.0, which was transformed from the FK4 system at B1950.0. The limitations and misunderstandings related to this transformed GalCS can be avoided by defining a new GalCS that is directly connected to the International Celestial Reference System (ICRS). With more data at various wavelengths released by large survey programs, a more appropriate GalCS consistent with features associated with the Milky Way can be established. We try to find the best orientation of the GalCS using data from two all-sky surveys, AKARI and WISE, at six wavelengths between 3.4 μm and 90 μm, and synthesize results obtained at various wavelengths to define an improved GalCS in the framework of the ICRS. The revised GalCS parameters for defining the new GalCS in the ICRS are summarized as: αp = 192.777°, δp = 26.9298°, for the equatorial coordinates of the north Galactic pole and θ = 122.95017° for the position angle of the Galactic center. As one of the Galactic substructures, the Galactic warp exhibits different forms in different GalCSs that are constructed with various data and methods, which shows the importance of re-defining the GalCS by the relative commission of the International Astronomical Union that can lead to a better understanding of Galactic structure and kinematics.


Keywords astrometry — catalogs — Galaxy: general — reference system

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