A new estimate of the zero-point shift of the Gaia DR3 parallaxes obtained from a comparison with VLBI measurements of masers and radio stars

Abstract

The most complete sample of radio stars and masers with trigonometric parallaxes measured by the VLBI method, common with the Gaia EDR3 and Gaia DR3 catalogs, has been compiled using literature data. The sample contains 151 stars. An analysis of the differences in parallaxes and proper motions of Gaia-VLBI stars has been performed. A new estimate of the systematic shift of the Gaia parallax zero point relative to the inertial coordinate system has been obtained: $Δπ=-0.038\pm0.011$ mas. The obtained estimates of the relative rotation rates confirm the absence of a significant rotation of the Gaia\,DR3 system relative to the extragalactic coordinate system, which in this case is represented by VLBI measurements.

Figures (3)

• Figure 1: Parallaxes of radio stars from the Gaia DR3 catalogue depending on their VLBI parallaxes, the solid line corresponds to a correlation with a coefficient of 1, the dotted lines correspond to the results of solving equation (\ref{['EQ-1']}) using these data (see table \ref{['t-pi-1']}).
• Figure 2: Parallax differences of stars of the type "Gaia--VLBI".
• Figure 3: Differences in the proper motions of stars of the type "Gaia--VLBI".