Distribution of the library spectra in the region of the parameter space occupied by the cluster stars. The gray dots represent the H16 measurements of the cluster members. The top graphics are the projections in the log g vs. T_eff plane and the bottom graphics show the [Fe/H] vs. T_eff projections. The overplotted colored points are the location of the reference spectra in the three libraries used in this paper. Left panel: Göttingen Spectral Library used by H16, central panel: ELODIE library, and right panel: MILES library. These last two libraries were used in tour reanalysis. Only the library stars corresponding to the region mapped by the our sample are shown: T_eff <  7000 K, and −3.04 <  [Fe/H] <  −0.88 dex (77 stars for ELODIE and 137 for MILES, including 40 and 46 stars, respectively with [Fe/H] < −1.7 dex). The color scales for the ELODIE and MILES libraries are indicated on the right.