Spectral observations of binary systems with relativistic partners at the 6-m telescope

ResulTs of spectral observations of binary systems with relativistic partners at the 6-m telescope are discussed. The aim of investigating bright objects is to determine all physical parameters of optical partners, structure and their atmoSphere nonstationarity, the rate of mAss loss, estimations of orbits and relativistic partner masses; of weak objects - to determine primarily optical partner physical parameters. Two most interesting objects FCygnus X-1 and SS 433 are considered in detail