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Pioneer 11 CRT Cruise Data Archive


Availability: At NSSDC, Ready for Electronic Access

Time span: 1973-04-06 to 1994-07-01


This dataset from the Cosmic Ray Telescope (CRT) experiment primarily contains interplanetary cruise data at six hour resolution with additional encounter data at 15 minute resolution. SDFU metadata files give detailed descriptions of the spacecraft, CRT experiment, measured parameters, and the data format. Each tape volume consists of two metadata files followed by data files covering the first or second half of each year of the mission. Measured differential fluxes for solar and galactic cosmic ray protons, helium, and electrons are given at subintervals within energy ranges of 3-227 MeV, 3-413 MeV, and 2-6 MeV, respectively, with flux units of particles/(cm**2-s-sr-MeV/nucleon) for ions and particles/(cm**2-s-sr-MeV) for electrons. Integral counting rates of protons, helium, heavy ions, electrons, and energy deposition thresholds in various CRT detectors are also given. Each data record consists of 1024 ASCII characters which include one time field, eight flux fields, and 30 rate fields. The starting time of each six-hour averaging interval is expressed in CCSDS Time Code format (e.g., 1972-04-01T00:00 for April 4, 1974 at 00:00 hours) with respect to Spacecraft Event Time - UT. All flux and rate fields consist of two sub-fields for the average value and standard deviation of the measured parameter. Fluxes and rates were calculated initially from counts and accumulation times in 15 minute blocks with time boundaries at one minute resolution. Data gaps are denoted by the value "-1" in the error sub-field. A zero in the error sub-field indicates that the quantity was measured but no counts were detected. There are no delimiters at sub-field or field boundaries, nor is there any terminator for each data record.

These data are accessible on-line at:

Alternate Names

  • 6 hour CRT Interplanet Data,SFDU


  • Space Physics: Heliospheric Studies


  • 73-019A-12D

Additional Information



Questions and comments about this data collection can be directed to: Dr. John F. Cooper



NameRoleOriginal AffiliationE-mail
Dr. Frank B. McDonaldData ProviderUniversity of Maryland
Dr. Nand LalGeneral ContactNASA Goddard Space Flight Center
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