Spectroscopy of Giants of the Sagittarius Dwarf Galaxy

In this paper we present the first results of the analysis of intermediate resolution (Δλ ～ 3.5 Å) spectra of giants of the Sagittarius dwarf galaxy acquired using the ESO NTT telescope. From the deep CCD photometry of Marconi et al. (1998a) we have selected a sample of giants representative of the metallicity spread suggested by the comparison of the colour-magnitude diagram of Sagittarius with those of galactic globular clusters. The spectra have been used to measure radial velocities, to confirm the membership to Sagittarius, and to provide a metallicity estimate by using spectral synthesis techniques. The analyzed stars show a spread in metallicities in the range ?1.0≤ Fe/H]≤ +0.7, some 0.5 dex more metal-rich than the photometric estimates.