In this exploration of the photoelectron spectrum of the ozone molecule, we have deployed cutting-edge high-order CC models together with a vibronic Hamiltonian approach to spectroscopy beyond the Born-Oppenheimer approximation . We parameterized the Hamiltonian using EOM-IP-CC calculations and the formalism of quasi-diabatic states of Ichino, Gauss and Stanton. The results of the simulation are in excellent agreement with the experimental spectrum from the ionization onset to about 2,500 cm -1 higher (the restriction arising from the local parametrization of the Hamiltonian). Analysis of the spectrum and its simulation underscore the importance of vibronic coupling effects in the ozone cation.