Plasma parameters as observed by RPC during the main event. Panel a: magnetic field components and magnitude (black). Panel b: cone and clock angle of the magnetic field. Panel c: estimates of the plasma density from different instruments. IES observations are energy-summed flux adjusted to fit the scale. Panels d and e: electron and ion flux integrated over the entire field of view of IES. Panel f: spacecraft potential (multiplied by − 2 for clarity) derived from LAP sweeps and ion energy spectrogram measured by ICA. The vertical lines indicate the boundaries of the three plasma regions (indicated by numbers at the bottom).