MUSICOS : a fiber-fed spectrograph for multi-site observations.

This paper describes a fiber fed echelle spectrograph designed and constructed at the Paris-Meudon Observatory. This instrument is designed for the MUSICOS project, whose purpose is to organize multisite continuous spectroscopic observations. The optical scheme is described in some detail, as well as the data reduction software. We give a review of the spectrograph main performances which were obtained during laboratory tests and in real observational conditions at the 2 m diameter telescope at Pic du Midi (France).