grvs_mag computed following the procedure outlined in Sect. 4.2, , plotted against true magnitude, , for the simulations described in Sect. 6. The red line shows the median relation from 1000 realisations, and the shaded area the associated error. The dashed blue line shows the identity relation. The estimated magnitude becomes systematically brighter than the true one for . The limiting magnitude of the stars processed for DR3 corresponds to .