Previously identified variable and nonvariable PG 1159 stars and variable [WCE] stars in the log T_eff − log g diagram. The thin solid curves show the post-born again evolutionary tracks from Miller Bertolami & Althaus (2006) for different stellar masses. “Hybrid” refers to PG 1159 stars exhibiting H in their atmospheres, and “N.V.D.” means no variability data (which only applies to SDSS J152116). The location of the GW Vir star NGC 246 is shown as the large red star with error bars. This star is characterized by T_eff = 150 000 ± 10 000 K and log g = 5.7 ± 0.10.