0720025

LSI+61 303 is one of the few binary systems with a compact object and Be star from which unpulsed X-ray and radio as well as the high-energy gamma-ray (GeV TeV) emission has been observed. The system is also known to emitAU-scale jet which makes it a candidate for a Galactic microblazar. The system lightcurves in different energy ranges show a puzzling behaviour with the X-ray maxima shifted with respect to the radio maxima and the maximaphase shifting from orbit to orbit. The origin of the compact source (neutron star or black hole) is not known yet and neither we are sure on the energy of the electrons producing the observed X-ray emission. The goal of this proposal is to study for the first time the spectrum of the source in hard X-rays (above 50 keV) and its variability on the orbital timescale. This information along with the simultaneous observations in GeV energy band by FERMI will give us a clue to the physical processes taking place in the system and the possibility to built the emission formation model. [truncated! Please see actual data for full text]