  A new Monte Carlo program for photohadronic interactions of relativistic
nucleons with an ambient photon radiation field is presented. The event
generator is designed to fulfil typical astrophysical requirements, but can
also be used for radiation and background studies at high energy colliders such
as LEP2 and HERA, as well as for simulations of photon induced air showers.
  We consider the full photopion production cross section from the pion
production threshold up to high energies.
  It includes resonance excitation and decay, direct single pion production and
diffractive and non-diffractive multiparticle production.
  The cross section of each individual process is calculated by fitting
experimental data, while the kinematics is determined by the underlying
particle production process. We demonstrate that our model is capable of
reproducing known accelerator data over a wide energy range.
