The Gaia reference frame for bright sources examined using VLBI observations of radio stars

Abstract

Positions and proper motions of Gaia sources are expressed in a reference frame that ideally should be non-rotating relative to distant extragalactic objects, coincident with the International Celestial Reference System (ICRS), and consistent across all magnitudes. For sources fainter than 16th magnitude this is achieved thanks to Gaia's direct observations of quasars. At brighter magnitudes it is difficult to validate the quality of the reference frame due to the scarcity of comparison data. This paper examines the use of VLBI observations of radio stars to determine the spin and orientation of the bright reference frame of Gaia. Simultaneous estimation of the six spin and orientation parameters makes optimal use of VLBI data and makes it possible to include even single-epoch VLBI observations in the solution. The method is applied to Gaia Data Release 2 (DR2) using published VLBI data for 41 radio stars. Results for the 26 best-fitting sources indicate that the bright reference frame of Gaia DR2 is rotating relative to the faint quasars at a rate of about 0.1 mas/yr, significant at 2-sigma level. This supports a similar conclusion based on a comparison with stellar positions in the Hipparcos frame. The accuracy is currently limited by the small number of radio sources used, by uncertainties in the Gaia DR2 proper motions, and by the astrophysical nature of the radio stars. While the origin of the indicated rotation is understood and can be avoided in future data releases, it remains important to validate the bright reference frame of Gaia by independent observations. This can be achieved using VLBI astrometry, which may require re-observing the old sample of radio stars as well as measuring new objects. The unique historical value of positional measurements is stressed and VLBI observers are urged to ensure that relevant positional information is preserved for the future.

17 pages, 5 figures. Revised version incorporating a Corrigendum published by A&A. Tables 2-3, Figures 3-5, and Sections 3-5 have been substantially revised

References in corpus (27)

• Gaia Data Release 2. Summary of the contents and survey properties
• The Gaia mission
• Gaia Data Release 2: The astrometric solution
• Gaia Data Release 2: Photometric content and validation
• Gaia Data Release 2: Catalogue validation
• Gaia Data Release 1: Astrometry - one billion positions, two million proper motions and parallaxes
• Milky Way Cepheid Standards for Measuring Cosmic Distances and Application to Gaia DR2: Implications for the Hubble Constant
• Gaia Data Release 1: Catalogue validation
• The Hipparcos-Gaia Catalog of Accelerations
• The Gould's Belt Distances Survey (GOBELINS) II. Distances and structure towards the Orion Molecular Clouds
• Gaia Data Release 2: The Celestial reference frame (Gaia-CRF2)
• VLBA determination of the distance to nearby star-forming regions I. The distance to T Tauri with 0.4% accuracy
• The Gould's Belt Distances Survey (GOBELINS) I. Trigonometric parallax distances and depth of the Ophiuchus complex
• Confirmation of the $Gaia$ DR2 parallax zero-point offset using asteroseismology and spectroscopy in the $Kepler$ field
• The Gould's Belt Distances Survey (GOBELINS). V. Distances and Kinematics of the Perseus molecular cloud
• Distances and parallax bias in Gaia DR2
• A VLBI Resolution of the Pleiades Distance Controversy
• The Gould's Belt Distances Survey (GOBELINS). IV. Distance, Depth and Kinematics of the Taurus Star-Forming Region
• The Gould's Belt Distances Survey (GOBELINS) III. The distance to the Serpens/Aquila Molecular Complex
• Improved VLBI astrometry of OH maser stars
• Comparison of Gaia DR2 Parallaxes of Stars with VLBI Astrometry
• Rigorous treatment of barycentric stellar motion: Perspective and light-time effects in astrometric and radial velocity data
• On-orbit performance of the Gaia CCDs at L2
• Radio Stars: from kHz to THz
• VLBI Astrometry of AGB Variables with VERA -- A Mira Type Variable T Lepus
• Orbital Motion of Young Binaries in Ophiuchus and Upper Centaurus-Lupus
• Residual HCRF Rotation relative to the Inertial Coordinate System

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