Distributions of electron plasma oscillations upstream from the Earth's bow shock

We present data from the 14.5- and 30-kHz plasma-wave detector channels aboard Ogo 5 for the period December 2, 1968, to April 8, 1969, to demonstrate the relatively isotropic occurrence of electron plasma oscillations upstream from the bow shock. These plasma oscillations were shown previously to correlate with streams of electrons having energy >700 ev. The present study implies the presence of such streams, most probably electrons reflected by the bow shock, irrespective of spacecraft longitude in the upstream solar wind.