Medium-resolution spectroscopy of galaxies with redshifts 2.3 < z < 3.5

Using FORS2 at the ESO VLT we obtained medium resolution (R ~ 2000) spectra of 12 galaxies with 2.37 3 have lower mean metallicity than galaxies at 2.5 < z < 3. However there remain uncertainties concerning the absolute calibration of the metallicity tracers in use for high-redshift galaxies. Additional modeling will be needed to resolve these uncertainties.