Data Products of the IMP-8 GME:

Selected Instrument Rates


  1. Data Content and Usage
  2. Graphical Access
  3. Digital Data Access


  • These data should be considered a "browse" or "quicklook" data product
  • Data consist of 5 hourly-average key GME rates that characterize the interplanetary environment
  • Selected instrument rate data run from the first GME data in Oct 1973 to "the present"
    • There is a typical time delay in posting new data of 1-2 months (e.g. as of 5/1/97, data to 3/21/97 are available). This delay is due primarily to the schedule on which IMP-8 telemetry data is collected and shipped.
  • Selected GME Instrument rates are available both in graphical and digital form

1. Data Content and Usage (Selected Rates)

  • The five rates of this data product are:
    • >60 MeV ions from the G anti-coincidence MED rate
    • 20-80 MeV protons from the D.E.-F.-G event-type MED rate
    • 0.5-4 MeV protons from the A.-B.-C event-type LED rate
    • 1.7-12.8 MeV/nuc He from the S1D event-type VLET rate
    • >3.7 MeV/nuc ions Z>=6 from the S2D event-type VLET rate

    Units of rates are counts/second. Statistical uncertainties are supplied with the rates. There is no normalization for instrument geometry factor applied. This data in graphical does have scaling factors applied to several rates to better separate the traces on the plot. The MED, LED and VLET are GME detector subsystems; please see the instrument description page for additional detail.

    The identification of rate data with any specific type of particle is ONLY APPROXIMATE and may NOT be relied upon for anything but a general characterization of the interplanetary environment at IMP-8. It is for this reason that the data are classified as a "browse" or "quicklook" data product that should be used only with a clear understanding of what such data may or may not include. All rate data is subject to extensive contamination for multiple species, the fraction of which may change depending ambient conditions. Solar energetic particle event onset behavior will differ from behavior near peak fluxes, from particles associated with interplanetary shock fronts (which typically have very steep spectra) from quiet times.

    Data are produced as linear averages of observed rates for times when data are being collected. There is no attempt to interpolate to fill data gaps in producing these averages.


2. Graphical Access (Selected Rates)

  • The hourly-averaged rates are pre-plotted on successive 10-day periods for the life of the mission (1973-present). Several rates have scaling factors assigned. A simple interface is the
    Primary plot display interface

    mechanism but

    Directory of "gif" image files (for file transfer)

    is also supported. The file naming convention for these plots is IMP8_GME_YYSSS_YYEEE.gif where SSS is the start julian day of the plot, EEE the end julian day and the respective "YY's" the start and end (2-digit) years.


3. Digital Data Access (Selected Rates)

  • Selected hourly-average rate data are available as ASCII files of length <=90 days for the life of the mission (1973-present). The files are structured as 1 file/rate with each line of the file the time, rate and uncertainty in the rate in units of counts/second. The plot scaling factors are NOT applied to the digital form of these rates (i.e. the rates are true).

    These rate data is accessible at

    Directory of Rate Files (for file transfer)

    The file naming for the digital rates is YYYY_SSS_EEE_RATEID, where RATEID is as labeled on the plots and one of

RATEID (in file label)
Dominant Energy and Species

>60 MeV/nuc ions
20-80 MeV protons
0.5-4 MeV protons
1.7-12.6 MeV/nuc He
>3.7 MeV/nuc Z>=6

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Questions or Comments

Contact Information

Questions about GME data and/or instrumentation should be directed to the NASA Principal Investigator:

Dr. Robert E. McGuire (at
Head, Space Physics Data Facility
Code 672
NASA/Goddard Space Flight Center
Greenbelt MD 20771 USA
Phone (with phonemail): 301-286-7794

Authors/Authorizing NASA Official and Curator

Dr. Robert McGuire (see above)

Last Modified: 7/21/98 REM