The latitude and radial dependence of shock acceleration in the heliosphere.

Voyagers 1 and 2 have observed interplanetary shock acceleration of ~ 2 MeV ions ac radial distances of > 25 AU and heliographic latitudes of up to ~ 30degrees. The previously reported negative latitude gradient in the intensities of accelerated ions ac these energies persists over the entire range of latitudes and radial distances measured. The energy spectra of the shock acceleration events at voyagers 1 and 2 are similar.