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ACE SEPICA 120-sec Particle Fluxes, HDF


Availability: At NSSDC, Ready for Electronic Access

Time span: 1997-10-07 to 2002-08-23


This data collection contains 120-sec Level 2 data in binary Hierarchical Data Format (HDF) format from the Solar Energetic Particle Ionic Charge Analyzer (SEPICA) instrument on the Advanced Composition Explorer (ACE) spacecraft. This data set includes all measurements from solar quiet and active periods. Each data file covers one 27-day Bartels interval of solar rotation. Data records contain 120-sec time averages of hydrogen and helium ion fluxes in units of particles/(cm2*sr*sec*Mev/nucleon). There are three energy channels for H ions at 0.7 - 3 MeV and eight for He ions at 0.4 - 2 MeV/nucleon. Two of the He channels include contributions from a Am-241 calibration source in SEPICA and are dominated by source events during quiet times. A data value of -999.9 indicates bad or missing data for the given time period. The number of counts is also given from which the statistical uncertainties can be calculated. Statistical flux uncertainties are computed from flux/sqrt (N), where N is the number of counts or events during the averaging period. Current release notes on Level 2 processing are given in the text file sepica_release_notes.txt, and sepica_energy_bands.txt defines the energy ranges and mean energies for each data channel.

This collection is available on-line at:

Alternate Names

  • SEPICA Level-2 120-sec Flux, HDF


  • Space Physics: Heliospheric Studies


  • 97-045A-04A

Additional Information



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



NameRoleOriginal AffiliationE-mail
Dr. Andrew J. DavisGeneral ContactCalifornia Institute of
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