﹩{T}_{\mathrm{eff}}﹩–﹩\mathrm{log}g﹩ diagram of the ZZ Ceti stars. The black points correspond to the 172 known ZZ Ceti stars with determined atmospheric parameters. The open squares with error bars mark the two positions of J004628 with different atmospheric parameters and the filled squares with error bars correspond to the three new ZZ Ceti stars. The empirical boundaries of the ZZ Ceti instability strip are marked with the dashed lines.