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Triaxial Search-Coil Magnetometer

NSSDC ID: 1964-054A-01
Mission Name: OGO 1
Principal Investigator: Dr. Edward J. Smith


The OGO 1 Triaxial Search Coil Magnetometer was designed to measure the magnetic field fluctuations from 0.01 to 1 kHz. Due to a spacecraft malfunction, the OGO satellite assumed a spin-stabilized mode with a 12-s period. This meant the magnetometer output was modulated with an approximately sinusoidal signal, providing a measure of the dc component of the magnetic field perpendicular to the spin axis as well as the ac data. The magnetometer assembly was on a 6.1-m boom, and the electronics were in the body of the spacecraft. The sensitivity was 10 microvolts/nT-s. The low-frequency channel was sampled five times every 1.152 s by the telemetry system when the data rate was 1 kbs, and proportionally faster for the higher telemetry rates of 8 and 64 kbs. However, due to the spacecraft spin, the highest bit rate could not be used when the satellite was more than 10 earth radii away. The upper frequency cutoff (to avoid aliasing in the data) was 2 Hz for the 1- and 8-kbs telemetry rates, and 130 Hz for the 64-kbs rate. The high-frequency channel provided spectral analysis information for frequencies from 1 to 10 kHz in five steps. The experiment operated satisfactorily, averaging about 4000 h of data per year. More details regarding experiment design may be found in Frandsen, A. M. A., IEEE Trans. on Geosci. Electron., v. GE-7, n. 2, pp. 61-74, April 1969.


  • Space Physics: Heliospheric Studies
  • Space Physics: Magnetospheric Studies

Additional Information

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



NameRoleOriginal AffiliationE-mail
Prof. Robert E. HolzerOther InvestigatorUniversity of California, Los Angeles 
Dr. Edward J. SmithPrincipal InvestigatorNASA Jet Propulsion

Selected References

Frandsen, A. M. A., et al., OGO search coil magnetometer experiments, IEEE Trans. Geosci. Electron., GE-7, 61-74, Apr. 1969.

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