Distance versus effective temperature curves corresponding to evolutionary sequences of PG1159 models extracted from Miller Bertolami & Althaus (2006) with different stellar masses and the apparent magnitude V corresponding to the GW Vir star (PNNV-type) NGC 6905 (red circle with error bars), characterised by T_eff = 141 000 ± 10 000 K and d_BJ = 2700 ± 200 pc. From linear interpolation, the astrometric mass of NGC 6905 is $M_{\mathrm{Astr}}=0.{668}_{-0.044}^{+0.063}{M}_{\odot }$.