Distance versus effective temperature curves corresponding to evolutionary sequences of DB WD models extracted from Althaus et al. (2009) with different stellar masses and the apparent magnitude V of the DBV star GD 358 (red circle with error bars), characterised by T_eff = 24 937 ± 1018 K and d_BJ = 42.99 ± 0.05 pc. The uncertainty in the distance is so small that it is contained within the symbol. From linear interpolation, the astrometric mass of GD 358 is $M_{\mathrm{Astr}}=0.{616}_{-0.017}^{+0.016}{M}_{\odot }$.