  The $e^+e^-$ invariant mass distribution spectra are calculated to estimate
the hadron parameters of the $\rho$ meson produced coherently in the
photonuclear reaction. The elementary reaction occurring in the nucleus is
considered to proceed as $ \gamma N \to \rho^0 N ; ~ \rho^0 \to e^+e^- $. We
describe the elementary $\rho$ meson photoproduction by the experimentally
determined reaction amplitude $ f_{ \gamma N \to \rho^0 N } $. The $\rho$ meson
propagator is presented by the eikonal form, and the $\rho$ meson nucleus
optical potential $V_{O\rho}$ appearing in it is estimated using the
"$t\varrho$" approximation. The $\rho$ meson nucleon scattering amplitude $ f_{
\rho N } $ extracted from the measurements is used to generate this potential.
The calculated $e^+e^-$ invariant mass distribution spectra are compared with
those measured at Jefferson Laboratory. The calculated results for the
transparency ratio are also presented.
