  Within the framework of a flat cosmological model a propagation of an
instantaneous burst of nonpolarized isotropic radiation is considered from the
moment of its beginning at some initial redshift z0 to the moment of its
registration now (at z=0). Thomson (Rayleigh) scattering by free electrons is
considered as the only source of opacity. Spatial distributions of the mean
(over directions) radiation intensity are calculated as well as angular
distributions of radiation intensity and polarization at some different
distances from the center of the burst. It is shown that for redshifts z0 large
enough (z0 > 1400) the profile of the mean intensity normalized to the total
number of photons emitted during the burst weakly depends on initial conditions
(say the moment z0 of the burst, the width and shape of initial radiation
distribution in space). As regards angular distributions of intensity and
polarization they turn to be rather narrow (3 - 5 arcmin) while polarization
can reach 70%. On the average an expected polarization can be about 15%.
