Evidence for a systematic offset of -80 micro-arcseconds in the Gaia DR2 parallaxes

Abstract

We reprise the analysis of Stassun & Torres (2016), comparing the parallaxes of the eclipsing binaries reported in that paper to the parallaxes newly reported in the Gaia second data release (DR2). We find evidence for a systematic offset of $-82 \pm 33$ micro-arcseconds, in the sense of the Gaia parallaxes being too small, for brightnesses $(G \lesssim 12)$ and for distances (0.03--3 kpc) in the ranges spanned by the eclipsing binary sample. The offset does not appear to depend strongly on distance within this range, though there is marginal evidence that the offset increases (becomes slightly more negative) for distances $\gtrsim 1$ kpc, up to the 3 kpc distances probed by the test sample. The offset reported here is consistent with the expectation that global systematics in the Gaia DR2 parallaxes are below 100 micro-arcseconds.