This dataset contains start and stop times/locations where
superthermal ions were detected by the Neutral Mass Spectrometer
instrument aboard the Pioneer Venus Orbiter. The instrument detected
superthermal, energetic or fast ions whose energy exceeds 36 eV in
the spacecraft frame of reference. These ions were observed in
early orbits during measurements of the neutral density near
periapsis, have an erratic and unpredictable signature, and occur
at too high an altitude to be due to the neutral atmosphere. When the
altitude of periapsis increased above the point where neutral density
measurements could be made, the instrument was configured
specifically to detect superthermal ions. In general, for orbit
numbers 1 to 645, data were taken from the RPA mode. The gas
background signal with the filament on is about a factor of 10
less in this mode than in non-RPA mode, resulting in a lower
detection threshold. For orbit numbers above 923, the instrument
was deliberately configured with the filament off and non-RPA
mode data was used. For mass 16 the RPA voltage is about +3.8
volts.