Comparison of simulations with observations. Left panel: time evolution of the proton energy spectrum at the shock in the simulation for ϵ_inj = 6 × 10⁻³ (colored lines) superposed on the spectrum obtained from the observations (crosses). The indicated simulation times are in arbitrary units. Also shown is the seed particle spectrum as computed in the shock frame (black dashed line) and in the spacecraft frame (solid black line). See the main text for further details. Right panel: simulated proton distributions along the magnetic field line at t_sim = 16 [arbitrary units] (solid lines) vs. the distributions obtained from the observations (dotted lines).