Gaia's DR1 parallaxes vs previous measurements

We find that the Gaia parallaxes are, on average, 0.24+/-0.02mas smaller than the weighted mean trigonometric parallax values for these stars in the solar neighborhood. We also find that the offset changes with distance out to 100pc, in the sense that the closer the star, the larger the offset.

We find no systematic trends in the parallax offsets with stellar V magnitude, V-K color, or proper motion. We do find that the offset is roughly twice as large for stars south of the ecliptic compared to those that are north.