Comparison of Gaia DR2 Parallaxes of Stars with VLBI Astrometry

Understand

We compare the parallaxes of stars from VLBI astrometry in the literature to those in the Gaia DR2 catalog.

• Our full sample contains young stellar objects, evolved AGB stars, pulsars and other radio stars.
• Excluding AGB stars, which show significant discrepancies between Gaia and VLBI parallaxes, and stars in binary systems, we obtain an average, systematic, parallax offset of $-75 \pm 29~\mu$as for Gaia DR2, consistent with their estimate of a parallax zero-point between $-100$ and 0 $\mu$as.