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Apollo 12 ALSEP Solar Wind Spectrometer 28-second Data (PDS)


Availability: Archived at NSSDC, accessible from elsewhere

Time span: 0069-11-19 to 0076-03-25


This PDS data set contains daily tables of time ordered, 28-second-resolution plasma parameters, mainly of the solar wind, as observed on the Moon at the Apollo 12 ALSEP site by the Apollo 12 Solar Wind Spectrometer (SWS) from 19 November 1969 through 25 March 1976. This is the highest resolution data set available from the SWS instrument.

The 28-second SWS data tables are in fixed-width ASCII format. There is one table for each daily set of SWS measurements.

Each daily table contains a sequence of plasma measurements made every 28.1 seconds. Each record in a table provides the time of a measurement, proton density, alpha-to-proton ratio, proton bulk speed, and angle of flow. Each record identifies the Faraday cup on the side of the instrument (one of six) that measured the most charge. The measured charge of this cup, the adjacent side cups, and the vertical (top) cup are included in each record as well as the most probable thermal speed, and various housekeeping and fit parameters relating to the reliability of the calculated plasma parameters. Note that a value of 99.0 in Column 14, the Percentage Error in Fitting Program, indicates the fit was bad and thus all computed plasma parameters in that row are invalid.

These data tables were converted from the CDF format which was created from the original binary data set PSFP-00118 by the NSSDC as part of the Lunar Data Restoration project. The original tapes were written in BCD format on a UNIVAC 1108 computer.

This is PDS Data Set ID A12A-L-SWS-3-SOLAR-WIND-28S-RES-V1.0 held on Volume A12SW_0001 . The data are available online at:

Alternate Names

  • A12A-L-SWS-3-SOLAR-WIND-28S-RES-V1.0


  • Planetary Science: Fields and Particles

Additional Information



Questions and comments about this data collection can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Dr. Conway W. SnyderData ProviderNASA Jet Propulsion Laboratory
Dr. David R. WilliamsGeneral ContactNASA Goddard Space Flight
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