Gaia Data Release 2: Catalogue validation

TL;DR

This paper details the validation processes for Gaia DR2, assessing the accuracy, completeness, and limitations of the extensive astrometric, photometric, and spectroscopic data for over a billion sources.

Contribution

It provides a comprehensive validation framework and results for Gaia DR2, highlighting data quality, limitations, and guidance for scientific use.

Findings

High precision and large coverage of Gaia DR2 data

Identification of data anomalies and limitations

Guidance on proper data usage and caveats

Abstract

The second Gaia data release (DR2), contains very precise astrometric and photometric properties for more than one billion sources, astrophysical parameters for dozens of millions, radial velocities for millions, variability information for half a million of stellar sources and orbits for thousands of solar system objects. Before the Catalogue publication, these data have undergone dedicated validation processes. The goal of this paper is to describe the validation results in terms of completeness, accuracy and precision of the various Gaia DR2 data. The validation processes include a systematic analysis of the Catalogue content to detect anomalies, either individual errors or statistical properties, using statistical analysis, and comparisons to external data or to models. Although the astrometric, photometric and spectroscopic data are of unprecedented quality and quantity, it is shown that the data cannot be used without a dedicated attention to the limitations described here, in the Catalogue documentation and in accompanying papers. A particular emphasis is put on the caveats for the statistical use of the data in scientific exploitation.