On periodic γ radiation of Cygnus X-3

The periodic gamma-ray radiation with energy 108 and 1012 eV from the galactic source Cyg X-3 is analyzed. It is shown, that position of gamma-ray pulse at the light curve for the period P=1=48h (phase phi) depends on the interval of phases phi of the period P2=34.1 d, i.e. the pulse appears near the phase phi--0.2 if phi=0-0.5 and near phi=0.6 if phi=0.5-1.0. This dependence allows to remove the discrepancies between different experimental data and can be explained by relativistic precession of the orbit of the binary system the mass of which is approximately 103 M* (M* is the solar mass)