Change in Interplanetary Shock Acceleration Preceding STIP Interval XVII

The intensity and frequency of shock acceleration events in the interplanetary medium decreased dramatically in early 1985. Low energy ions were observed by IMP 8 at 1 AU and Voyagers 1 and 2 at 22 and 16 AU respectively. Voyager 1 was at 25 degrees heliographic latitude while IMP 8 and Voyager 2 were near the solar equatorial plane.