4MOST spectral data simulation

International audience4MOST is a phase A study of a very high-multiplex, wide-field fibre-fed spectrograph system for the VISTA or NTT telescope. The main stellar goal of the instrument is to complement and complete the informations on the Milky Way, that Gaia will provide both on radial velocity and chemical analysis. Two resolution modes (about 5000 and 20000) are foreseen to operate at the same time. We have developed a simulator of spectral data for the 4MOST spectrograph. This simulator produces mock scientic spectra to be analyzed by the science team in order to constrain the feasibility of their requirements and help refine the high-level specications of the instrument. We present here the spectra simulator and how some of the simulation results are used to define the performances of 4MOST