Example demonstrating how insufficient astrometric modelling leads to incorrect RV determinations. Top panel: motion of Gaia DR3 6631710606341412096 on the sky with respect to its reference position in the reference system moving with Gaia, as predicted from the five-parameter single-star AGIS solution (solid blue line), compared with the position predicted by the NSS AstroSpectroSB1 solution (dot-dashed red line), which included the Keplerian orbit. Circles show the positions at which the epoch RV were measured, and the arrows show the scanning direction at the epoch. Bottom panel: RV data, folded in phase, as provided by the DR3 pipeline (blue dots) and the data corrected for the displacement (in red), compared with the radial velocity predicted by the AstroSpectroSB1 solution (green line).