Kiel diagram and parameter uncertainties of our sample. Top: Kiel diagram of the entire spectroscopic sample. The parameters and their errors are derived with spectral synthesis. All spectra are color-coded by their global metallicity. Three examples of BaSTI isochrones, used when fitting with BASTA, are superimposed with different colors according to their ages and [Fe/H] values. They are zoomed-in around the evolutionary stage of our targets. Bottom: Relative uncertainties on T_eff and log g as a function of temperature and color-coded by the S/N of the targets.