Average of the computed period spacings, $\overline{\mathrm{\Delta }{\mathrm{\Pi }}_k}$, assessed in the range of periods observed in NGC 246, corresponding to our PG 1159 evolutionary sequences (with stellar masses expressed in solar units), in terms of the effective temperature. The thin curves represent the cases in which the period spacing is assumed to be associated with ℓ = 1 modes, while the thick curves are for ℓ = 2 modes. The location of NGC 246 (ΔΠ = 12.902 ± 0.045 s, T_eff = 150 000 ± 15 000 K) is emphasized using a black circle with error bars.