Abstract
The technique of spherical harmonics, both scalar and vector ones, has long been applied to analyze the astronomical data on a sphere, for example, in the representation of systematic errors, in stellar kinematics. Up to now, spherical harmonics have been used exclusively in heliocentric coordinate systems: the equatorial or Galactic one. To study the kinematics of the entire Galaxy (and not only the solar neighborhood), it is reasonable to pass to the Galactocentric coordinate system. The second release of the Gaia catalogue does not yet allow such an analysis to be performed for individual stars due to the relatively low accuracy of the parallaxes. However, such a study seems possible for globular star clusters, despite their small number. Although the kinematics of globular clusters was studied in detail in many papers, we want to test the method of analyzing the Galactocentric proper motions and radial velocities using spherical harmonics based on data from this catalogue.
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ACKNOWLEDGMENTS
We are grateful to the anonymous referees for their very useful critical remarks that allowed us to rewrite the original version of the paper.
We used the data from the Gaia mission of the European Space Agency (ESA) (Gaia Collaboration et al. 2016) processed by the Gaia Data Processing and Analysis Consortium (DPAC, Gaia Collaboration et al. 2018). The funding for the DPAC was provided by national institutions, in particular, the institutions participating in the Gaia Multilateral Agreement.
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Tsvetkov, A.S., Amosov, F.A. Using Spherical Harmonics in the Galactocentric Coordinate System to Study the Kinematics of Globular Star Clusters. Astron. Lett. 46, 509–517 (2020). https://doi.org/10.1134/S1063773720080058
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DOI: https://doi.org/10.1134/S1063773720080058