Left: density plot of the difference between T_eff and the corresponding temperature from the isochrones and the dispersion of T_eff between the three nodes (see text). The black points indicate the mean (in 100 K steps) and the error bars the standard deviations. Right: same, but for log  g. The black points indicate the mean (in 0.2 dex steps) and the error-bars the standard deviations.