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1 minute averaged field and plasma data for all orbit phases


Availability: At NSSDC, Ready for Electronic Access


This collection has monthly files of hourly IMP 8 magnetic field and plasma averages, in ASCII format, computed at GSFC/SECAA using as input both the 15.36 s magnetic field data and the 1 minute MIT plasma data. It has one record per minute, regardless of whether there were field and/or plasma data for that minute. In fact, there are no plasma parameters available when the spacecraft is on the magnetosphere side of the magnetopause.

The data also accessible from:

Users of this 1 min data set are urged to consult documentation about the input data sets by consulting the 00aareadme.txt files at for magnetic field and for plasma in the directory /sw_msheath_min/.

The IMP position data used in this data set correspond to the ephemeris developed by GSFC's Flight Dynamics Facility in 2005. This occasionally differs from earlier ephemerides for roughly the past 20 years by up to an Earth radius or so.

In addition to presenting the contents and format of the 1-min records of this data set, there are three aspects of the data preparation that we explain in detail at namely the building of the 1-min averages, the despiking of the MIT plasma data, and the flagging of data as being in the solar wind or not.

Alternate Names



  • Space Physics: Heliospheric Studies


  • 73-078A-01T
  • 73-078A-02O

Additional Information



Questions and comments about this data collection can be directed to: Dr. Natalia E. Papitashvili



NameRoleOriginal AffiliationE-mail
Dr. Natalia E. PapitashviliGeneral ContactQSS Group
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