Testing stellar proper motions of TGAS stars using data from the HSOY, UCAC5 and PMA catalogues

• Published in: Monthly notices of the Royal Astronomical Society Vol. 476; no. 2; pp. 2743 - 2750
• Main Authors: Fedorov, P N, Akhmetov, V S, Velichko, A B
• Format: Journal Article
• Language: English
• Published: Oxford University Press 11.05.2018
• Subjects: catalogues; astrometry; proper motions; reference systems
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/sty415

Abstract We analyse the stellar proper motions from the Tycho-Gaia Astrometric Solution (TGAS) and those from the ground-based HSOY, UCAC5 and PMA catalogues derived by combining them with Gaia DR1 space data. Assuming that systematic differences in stellar proper motions of the two catalogues are caused by a mutual rigid-body rotation of the reference catalogue systems, we analyse components of the rotation vector between the systems. We found that the ωy component of the rotation vector is ∼1.5 mas yr−1 and it depends non-linearly on stellar magnitude for the objects of 9.5–11.5 mag used in all three comparisons of the catalogues HSOY, UCAC5 and PMA with respect to TGAS. We found that the Tycho-2 stars in TGAS appeared to have an inexplicable dependence of proper motion on stellar magnitude. We showed that the proper motions of the TGAS stars derived using AGIS differ from those obtained by the conventional (classical) method. Moreover, the application of both methods has not revealed such a difference between the proper motions of the Hipparcos and TGAS stars. An analysis of the systematic differences between the proper motions of the TGAS stars derived by the classical method and the proper motions of the HSOY, UCAC5 and PMA stars shows that the ωy component here does not depend on the magnitude. This indicates unambiguously that there is a magnitude error in the proper motions of the Tycho-2 stars derived with the AGIS.