As a function of the distance from the cluster centre (r_c) this figure shows the distribution of v _⊥ , the velocity component perpendicular to the direction to the convergent point (upper panel); the absolute magnitudes M_V derived from the secular parallaxes (lower panel). White dwarf candidates with distances D > 46.3 pc from the Sun are additionally marked by larger circles. Spectroscopic binaries are marked by their numbers in Table 1. The red line shows an approximate fit to an empirical magnitude-distance relation explained in the text.