Coronal structure of the April 10, 1969 solar flare particle event

The April 10, 1969 flare particle event and its associated solar wind disturbance have been re-examined by combining Pioneers 6-9 and Explorer 34 observations of 10 MeV protons with measurements of solar wind plasma on the same spacecraft. The particle fluxes and plasma velocities are mapped back to the Sun and compared at the same time of observation to give the instantaneous coronal emission profiles of flare-accelerated protons and solar wind. While the plasma preferentially escapes over the flare site with a half width of approximately 500, the bulk of energetic particles escapes from a quiet coronal region, almost 1000 to the west of the flare site. The particle profiles reveal strong exponential longitudinal gradients in the corona, which persist up to 14 days after the flare. (author)