Distribution of longitudinal separation angles between observers’ magnetic footpoints and the associated flare location. Positive (negative) separation angles denote a magnetic footpoint connecting west (east) of the flare longitude. Top: all events, including separation angles of observers not observing an event. Below: longitudinal separation angles of observers who observe a ~100-keV electron event (blue), a ~1-MeV electron event (green), and a > 25-MeV proton event (yellow).