  Single-particle radiative mechanism of $\gamma$ emission embedded into the
pre-equilibrium exciton model is used to calculate the $\gamma$ emission from a
decay of $^{160}$Er$^{*}$ created in two different ways. The initial stage of a
reaction is described using momentum-space overlaps of colliding nuclei. We can
reproduce the main features of the observed $\gamma$ energy spectra including
the fact that the spectrum observed in more symmetric combination is slightly
harder than in the other case.
