Validation of Gaia DR3 Orbital Solutions

These systems are hierarchical triples, with inner binary separations of order 1au, and outer separations of 100-100000au. Leveraging the fact that the inner binary and outer tertiary should have nearly identical parallaxes, we use the sample to calibrate the parallax uncertainties for orbital and acceleration binary solutions.

We find that the parallax uncertainties of orbital solutions are typically underestimated by a factor of 1.3 at G>14, and by a factor of 1.7 at G=8-14. The true parallax uncertainties are nevertheless a factor of ~10 smaller than those of the single-star astrometric solutions for the same sources. The parallax uncertainties of acceleration solutions are underestimated by larger factors of 2-3 but still represent a significant improvement compared to the sources' single-star solutions.