Ion differential fluxes with the background removed versus energy per charge (black dots). The data shown here come from 21 March 2016 between 17:45 and 18:00 UTC, shown in Fig. 2. The red line represents the measurement sensitivity, indicating the minimum flux for an observation to be considered statistically different from the background. The dash grey lines represents the fitted function that we subtracted from the matrix. The fits are only shown for the relevant energies. The vertical dashed black lines are the estimated energies of O⁶⁺ and O⁵⁺, respectively. The vertical lines match the energy of the observed data points well. These estimated energies were calculated assuming a uniform solar wind speed between species. The vertical error bars are the 90% confidence interval computed during the background noise reduction, with the horizontal error bar representing the energy resolution.