A classifier for spurious astrometric solutions in Gaia EDR3

Understand

The Gaia early Data Release 3 has delivered exquisite astrometric data for 1.47 billion sources, which is revolutionizing many fields in astronomy.

• For a small fraction of these sources, the astrometric solutions are poor, and the reported values and uncertainties may not apply.
• Before any analysis, it is important to recognize and excise these spurious results - this is commonly done by means of quality flags in the Gaia catalog.
• Here, we devise a means of separating 'good' from 'bad' astrometric solutions that is an order of magnitude cleaner than any single flag: 99.3% pure and 97.3% complete, as validated on our test data.