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Low-Energy Auroral Particle Detector

NSSDCA ID: 1967-073A-11

Mission Name: OGO 4
Principal Investigator:Dr. Robert A. Hoffman


The auroral particles experiment contained eight detectors, each comprised of a cylindrical electrostatic analyzer with a channel electron multiplier. Seven of these detectors were capable of measuring ions or electrons as selected by ground command, and the eighth detector measured background. Five of the detectors looked along a vector pointing radially away from the earth, while three others looked out at 30 deg, 60 deg, and 90 deg to the radius vector pointing away from the earth. The look directions of all the detectors lay in a single plane. Four of the detectors that looked directly away from the earth measured electrons or ions at either 0.7, 2.3, 7.4, or 23.8 keV, and the fifth measured the background. Those detectors at other angles measured electrons or ions at 2.3 keV. Most of the data were taken over the north and south auroral zones and polar caps, but a small amount of lower latitude data was taken. The data taken over the south auroral zone amounted to less than 5% of the data. Since the earth's magnetic field is nearly vertical in the auroral zone, the detectors that pointed away from the earth measured precipitating particles, and the angled detectors measured particles having pitch angles nearly comparable to their respective spacecraft angles. The outputs of four of the detectors that pointed directly away from the earth were accumulated simultaneously into four logarithmic accumulators over precisely the same time interval, one half of a telemetry main frame. This was followed by the storage of the outputs of the four 2.3-keV angle detectors for precisely the same duration, one half of a telemetry main frame. This resulted in sampling rates for each detector including the background detector of 55.56 samples per s at 64 kbs, 13.89 samples per s at 16 kbs, and 3.47 samples per s at 4 kbs. All detectors, except for the 6-keV and the 90-deg, 2-keV, developed some noise problems preventing the measurement of small fluxes. Other than this, the detectors functioned normally. The experiment was operated in the electron mode continuously for about 6 days out of every 7. NSSDC has all the useful data that exist from this investigation.

Alternate Names

  • OGO4/Low-EnergyAuroralParticleDetector

Funding Agency

  • NASA-Office of Space Science Applications (United States)


  • Space Physics: Magnetospheric Studies

Additional Information

Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office



NameRoleOriginal AffiliationE-mail
Dr. Frederick W. BerkoGeneral ContactNational Security Agency
Dr. David S. EvansOther InvestigatorNOAA Environmental Research
Dr. Robert A. HoffmanPrincipal InvestigatorNASA Goddard Space Flight
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