During the first year of operation, the WIND spacecraft followed a complicated orbit which took it from the Earth to the upstream libration point and back again. During this time, a considerable number of upstream particle events were observed all the way out to the libration point. These events are typically of short duration (a few tens of minutes) and up until now have only been seen in the energetic protons (at energies of a few tens of keV, but extending up to several hundreds of keV). We present here new observations from the Three-dimensional (3D) plasma and energetic particle experiment on the WIND spacecraft of these upstream events, with particular emphasis on the uniqueness of the observations from this instrument: energy spectra measured over the range from a few keV to several hundreds of keV, and complete three-dimensional angular distributions covering the same range of energies. We present here for the first time a complete spectrum of these ions extending from a few eV to a few MeV. This spectrum, with a turnover at one or two keV, shows that the bulk of the energy density of the upstream ions is at around 1 keV. These are most likely the particles responsible for the low-frequency waves which are usually seen accompanying upstream events. [References: 9]
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