Velocity dispersion analysis of the velocity dispersion event. (a)–(g): proton fluxes measured by the northward telescope during the velocity dispersion event. The horizontal bar indicates the estimated most likely range of the peak time. (h): velocity dispersion analysis of the peak time t vs. the inverse of the velocity 1/V. The dashed line represents the linear regression to $t=t_0+L_0^{*}/V$, where t₀ is the peak injection time at the shock front, and the proton path length $L_0=L_0^{*}cos\text{PA}$, where the PA is ∼60° during this event.