Charge exchange ${\rho }^0{\pi }^{+}$ photoproduction and implications for searches of exotic meson

We analyze the process $\vec{\gamma }+p\to {\rho }^0{\pi }^{+}n$ at low momentum transfer focusing on a possibility of production of an exotic $J^{PC}=1^{-+}$ meson state. In particular we discuss polarization observables and conclude that linear photon polarization is instrumental for separating of the exotic wave.