Comparison for our sample stars between [Fe/H] from high resolution UVES measurements ([Fe/H]_HR) and that from the CaT with the calibration of Battaglia et al. (2008) ([Fe/H]_LR), as filled circles. For Sex24-72 HET/HRS spectroscopy at R ~ 18000 is used because CaT data are not available. Blue stands for the Sculptor’s stars, red for the Fornax’ star, and green is for Sextans’s ones. The CaT metallicity determined with the new calibration of Starkenburg et al. (2010) for low metallicities are shown as open circles. Crosses provide the same comparison at [Fe/H]  > −2.5, where the classical (old) CaT calibration is robust.