  For the kinematical region when a hard photon is emitted predominantly close
to the direction of motion of a longitudinally polarized initial electron and
relatively small momentum transfer to a proton we calculate the azimuthal
asymmetry of photon emission. It arises from the interference of the
Bethe-Heitler amplitude and those which are described by a heavy photon impact
factor. Azimuthal asymmetry does not decrease in the limit of infinite cms
energy. Lowest order expression for the impact factor of a heavy photon is
presented.
