Ion intensity measurements of the ESP event near Earth. (a) 5-min averages of the ion intensity-time profiles measured by ACE/EPAM for different energy channels. Far from the shock, the lowest energy channel of ACE/EPAM/LEMS120 departs from the nominal energy spectrum due to artificial counts produced by electrons bypassing the magnetic deflection system of LEMS120 (Marhavilas et al. 2015). The vertical lines indicate, from left to right, the onset of the ESP event, the shock arrival, and the leading edge of the flux rope. (b) Energy spectrum of the intensities observed by ACE/EPAM/LEMS120 and LEMS30, observed by ERNE/LED, and extracted from the SEPEM RDS v2.0 at the time of the shock arrival.