Left panel: K_s vs. J−K_s 2MASS based CMD of the cluster. The spectroscopic targets are marked with black empty squares. The field contaminant star is marked with a cross symbol. Right panels: log (g) vs. T_eff diagrams for the spectroscopic sample. PARSEC (Bressan et al. 2012) 13 Gyr isochrones for metallicity [M/H] = −0.9 dex and [M/H] = −1.1 dex are overplotted in the upper panel, while two isochrones of 11 and 13 Gyr with the cluster metallicity in the lower panel.