Position of the observed LRGB targets (red circles) in the T_eff-logg diagram. Blue and green squares are low- and high-C band CEMP stars, respectively. Two BaSTI theoretical isochrones (Pietrinferni et al. 2021) with an age of 12.5 Gyr, [Fe/H] =−3.2 and −1.5 dex, and an α-enhanced chemical mixture are shown as reference (blue curves). The predicted positions of the FDU completion and the RGB bump are marked as thick grey lines.