The metal abundances of NGC 188 and NGC 6791 from low-resolution spectra

Analysis of low-resolution spectra of K giants in the old open clusters NGC 188 and NGC 6791 yields [Fe/H] = 0.075 +/- 0.045 +/- sigma(sys) for NGC 188 and [Fe/H] = 0.320 +/- 0.023 +/- sigma(sys) for NGC 6791. The term sigma(sys) represents the drift between our underlying star catalog's abundance scale and the true abundance scale. Star R23 in NGC 6791 has [Fe/H] > 0.6 according to our analysis and deserves further study.