The notion of gravitational radiation as a radiation of the same level as the electromagnetic radiation is based on the theoretically proven and experimentally confirmed facts of the existence of stationary states of an electron in its gravitational field, characterized by the gravitational constant K = 1042 G (G is Newtonian gravitational constant) and unrecoverable space-time curvature Λ. These experimental facts include, in particular, data on the broadening of the spectra of the characteristic radiation of multielectron atoms. This broadening of the spectra can be only due to the additional broadening mechanism, in particular the presence of excited states of electrons in their gravitational field. Another fact is the new line in the X-ray emission spectrum according to the results of observation with MOS-camera of the XMM-Newton observatory. This line unlike other identified lines of electromagnetic radiation cannot be assigned to any atomic transition.