The MEPA instrument on the AMPTE/CCE Spacecraft provided ion angular distributions as rapidly as every 6 sec for H, He, and O at energies of 10 keV to 2 MeV in the dayside magnetosheath whenever the solar wind pressure compressed the magnetopause within 8.75 RE, the CCE apogee. In this report we discuss a burst of energetic particles in the subsolar magnetosheath and its association with rapid changes in the local magnetic field direction in such a way that the magnetic field connected the spacecraft to the magnetopause during the enhancement. We find that magnetosheath angular distributions outside the burst peaked at 90¿ pitch angles, whereas during the burst they exhibited field aligned streaming either parallel or antiparallel to the magnetic field combined with a clear earthward gradient. The clear earthward gradients at E≥10 KeV, the streaming, and the slope change in the burst-time magnetosheath spectrum at ~10 KeV suggest magnetospheric source for the burst-time≥10 KeV ions and heated solar wind for E<10 KeV. ¿ American Geophysical Union 1991