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Ion Comp. Moments & Mass/Energy Spectra, B-Field and Ephemeris Data


Availability: Archived at NSSDC, accessible from elsewhere

Time span: 1977-11-08 to 1982-03-20


Ion data from the Plasma Composition Experiment on ISEE-1 consist of a combination of (a) velocity moments for the four principal magnetospheric ion species H+, He++, He+, and O+, calculated in two different ways (using two different sets of assumptions) and covering the 0.01-0.1 and 0.1-16 keV/e energy ranges, (b) energy-angle spectra for the same four ions plus O++, covering the 0.01-17.9 keV/e range, and (c) mass spectra (<1 amu/e to about 150 amu/e) for four energy ranges, all derived once per each complete energy-mass scan cycle of the instrument, or once each 1- to 20-minute interval, depending on mode of operation, as well as (d) "total ion" moments, derived once per energy scan and assuming total count rate is due to H+ ions (0.1-16 keV). The energy-angle spectra (b) consist of spin-averaged count rates in 32 energy channels, plus the maximum count rate at each energy, the time and spin angle of this maximum, and the angular width of the count peak at 1/3 of maximum. In addition, magnetic field data (based on data from the magnetometer experiment) and spacecraft position information are also included. A User's Guide to the data is also included. All data, including the magnetic field data, have been screened very rigorously for potential telemetry problems; however, the magnetic field data are not as thoroughly processed as those archived by the magnetometer experiment Principal Investigator. Errors in the magnetic field data affect only part of the ion data, namely the beta value and the moments that are based on pitch-angle binning. The absolute calibration of the instrument is believed to have been accurate to better than 30% in the early phase of in-flight operations. Supplementary hard copy plots have also been provided and archived as data set 77-102A-12J. The instrument stopped operating in March of 1982.

Data are available online at

Alternate Names

  • Ion Comp Moments & Energy Spectra


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


  • 77-102A-12I

Additional Information



Questions and comments about this data collection can be directed to: Dr. H. Kent Hills



NameRoleOriginal AffiliationE-mail
Mr. Robert M. CandeyGeneral ContactNASA Goddard Space Flight
Dr. O. Walter LennartssonGeneral ContactLockheed Palo
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