Prognoz 10 observed a series energetic ion (E≥10 KeV) and electron (E≥30 KeV) burst whilst upstream of the dusk bow shock from 2000--2200 UT on June 7, 1985. The particles streamed away from the bow shock along the interplanetary magnetic field (IMF) during periods when the IMF connected the spacecraft to the bow shock/magnetosphere. Both ions and electrons were observed when the IMF connected the spacecraft to the subsolar bow shock, but only ions were observed when the IMF connected the spacecraft to the dusk bow shock. We present simultaneous ground and magnetospheric observations which indicate the onset of geomagnetic activity and an increase in magnetospheric energetic particle flux levels just prior to the series of particle bursts observed by Prognoz 10 upstream of the bow shock. The combined observations are consistent with a magnetospheric source for these upstream particle (E≥10 KeV) events. ¿ American Geophysical Union 1990