The curves for the estimation of the probability of SEP occurrence when both a CME and a solar flare have taken place, and thus the SXR magnitude (X-axis) and the longitude of a solar flare, as well as, the CME speed and AW are known. The figure presents the output of PROSPER for the case of E > 10 MeV with Halo CMEs (AW = 360°) and well-connected flares (lon ≥ 20°). Each fit corresponds to a solar flare class, color-coded as: C1.0 (black line), M1.0 (blue line), X1.0 (red line) and X10 (magenta line). The X-axis shows the speed of the CME (in km s⁻¹).