Electron and proton fluxes observed during the onset phase. Top panel: 1-min averaged electron fluxes observed by SolO/EPT, STEREO-A/SEPT, and SOHO/EPHIN together with 15-min averaged electron count rates measured by PSP/EPI-Lo. Bottom panel: 10-min averaged proton fluxes observed by SolO/HET, STEREO/HET, SOHO/ERNE and proton count rates measured by PSP/EPI-Hi. 3σ onset times are marked by dashed lines.