DATA SET OVERVIEW
  =================

    Version 1.1
    -----------
      This version 1.1 data set replaces the version 1.0 data set
      (DATA_SET_ID = VG1-J-LECP-4-15MIN) previously archived with
      the PDS.  Data records from the version 1.0 data set provided
      data for each of 8 sectors, plus the average for all sectors
      in a separate record for each channel.  This resulted in 9
      repeated times per channel.  Data records for the version 1.1
      data set provide all data for a given channel and time period
      (8 sectors, plus the average for all sectors) in a single
      record.  Other changes to this version include upgrading of
      the associated labels and templates to PDS version 3.2
      compliance, modification of the time formats and flag values.


    Data Set Description
    --------------------
      This data set consists of resampled data from the Low Energy
      Charged Particle (LECP) experiment on Voyager 1 while the
      spacecraft was in the vicinity of Jupiter.  This instrument
      measures the intensities of in-situ charged particles (>26 keV
      electrons and >30 keV ions) with various levels of
      discrimination based on energy, mass species, and angular
      arrival direction.  A subset of almost 100 LECP channels are
      included with this data set.  The LECP data are globally
      calibrated to the extent possible (see below) and they are time
      averaged to about 15 minute time intervals with the exact
      beginning and ending times for those intervals matching the
      LECP instrumental cycle periods (the angular scanning periods).
      The LECP instrument has a rotating head for obtaining angular
      anisotropy measurements of the medium energy charged particles
      that it measures.  The cycle time for the rotation is variable,
      but during encounters it is always faster than 15 minutes.
      Thus, the full angular anisotropy information is preserved with
      this data.  The data is in the form of 'rate' data which has
      not been converted to the usual physical units.  The reason is
      that such a conversion would depend on uncertain determinations
      such as the mass species of the particles and the level of
      background.  Both mass species and background are generally
      determined from context during the study of particular regions.
      To convert 'rate' to 'intensity' for a particular channel one
      performs the following tasks: 1) Decide on the level of
      background contamination and subtract that off the given rate
      level.  Background is to be determined from context and from
      making use of sector 8 rates (sector 8 has a 2 mm Al shield
      covering it).  2) Divide the background corrected rate by the
      channel geometric factor and by the energy bandpass of the
      channel.  The geometric factor is found in entry
      'CHANNEL_GEOMETRIC_FACTOR' as associated with each channel
      'CHANNEL_ID'.  To determine the energy bandpass, one must judge
      the mass species of the of the detected particles (for ions but
      not for electrons).  The energy band passes are given in
      entries 'MINIMUM_INSTRUMENT_PARAMETER' and
      'MAXIMUM_INSTRUMENT_PARAMETER' in table 'FPLECPENERGY', and are
      given in the form 'energy/nucleon'.  For channels that begin
      their names with the designations 'CH' these bandpasses can be
      used on mass species that are accepted into that channel (see
      entries 'MINIMUM_INSTRUMENT_PARAMETER' AND
      'MAXIMUM_INSTRUMENT_PARAMETER' in table 'FPLECPCHANZ', which
      give the minimum and maximum 'Z' value accepted -- these
      entries are blank for electron channels).  For other channels
      the given bandpass refers only to the lowest 'Z' value
      accepted.  The and passes for other 'Z' values are not all
      known, but some are given in the literature (e.g.
      [KRIMIGISETAL1979A]).  The final product of these instructions
      will be the particle intensity with the units: counts/(cm^2 str
      sec keV).


This figure represents the structure of a single data record. Note that the
'SECTOR_STRUCTURE' (SECTOR1, SECTOR2, etc.) are not columns, but rather a
grouping of the DATA_VALUE and STANDARD_DEVIATION columns.

            SECTOR1             SECTOR2                  AVERAGE
       __________________  __________________       __________________
 ____ | _____  _________ || _____  _________ |     | _____  _________ |
|    |||DATA ||STANDARD ||||DATA ||STANDARD ||     ||DATA ||STANDARD ||
|TIME|||VALUE||DEVIATION||||VALUE||DEVIATION|| ... ||VALUE||DEVIATION||
|____|||_____||_________||||_____||_________||     ||_____||_________||
      |__________________||__________________|     |__________________|

  Parameters
  ==========

    Electron Rate
    -------------
      Sampling Parameter Name           : TIME
      Data Set Parameter Name           : ELECTRON RATE
      Sampling Parameter Resolution     : 15.000000
      Sampling Parameter Interval       : 15.000000
      Data Set Parameter Unit           : COUNTS/SECOND
      Noise Level                       : 0.000000
      Sampling Parameter Unit           : MINUTE

      A measured parameter equaling the number of electrons hitting
      a particle detector per specified accumulation interval.  The
      counted electrons may or may not be discriminated as to their
      energies (e.g.  greater than E1, or between E1 and E2).


    Ion Rate
    --------
      Sampling Parameter Name           : TIME
      Data Set Parameter Name           : ION RATE
      Sampling Parameter Resolution     : 15.000000
      Sampling Parameter Interval       : 15.000000
      Data Set Parameter Unit           : COUNTS/SECOND
      Noise Level                       : 0.000000
      Sampling Parameter Unit           : MINUTE

      A measured parameter equaling the number of ions striking a
      particle detector per specified accumulation interval.  The
      counted ions may or may not be discriminated as to their
      energies (e.g.  energy/nucleon or energy/charge between E1
      and E2 or greater than E1) and/or as to their ion composition
      (atomic number Z or mass number greater than Z1 or M1, or
      between Z1 and z2 or M1 and M2).


  Source Instrument Parameters
  ============================
    Instrument Host ID                : VG1
    Data Set Parameter Name           : ION RATE
    Instrument Parameter Name         : ION RATE
    Important Instrument Parameters   : 1

    Instrument Host ID                : VG1
    Data Set Parameter Name           : ELECTRON RATE
    Instrument Parameter Name         : ELECTRON RATE
    Important Instrument Parameters   : 1


  Processing
  ==========
    Processing Level Id               : 4
    Software Flag                     : Y
    Processing Start Time             : 1988-08-01


    Processing History
    ------------------
      Source Data Set ID                : VG1-J-LECP-2-
      Software                          : PFAT:VGER
      Product Data Set ID               : VG1-J-LECP-4-15MIN


    Software 'PFAT:VGER'
    --------------------
      Software Name                     : PFAT:VGER
      Software Type                     : PIN
      Software Release Date             : N/A
      Node ID                           : N/A
      Cognizant Engineer                : N/A
      Software Access Description       : N/A


  Data Coverage
  =============

    Filename Records Start                     Stop
    -------------------------------------------------------------------
    T790228  2112    1979-02-28T00:00:11.000Z  1979-02-28T23:44:35.000Z
    T790301  2112    1979-03-01T00:00:11.000Z  1979-03-01T23:59:47.000Z
    T790302  1936    1979-03-02T00:15:47.000Z  1979-03-02T23:59:47.000Z
    T790303  1760    1979-03-03T00:15:23.000Z  1979-03-03T23:59:47.000Z
    T790304  1892    1979-03-04T00:19:23.000Z  1979-03-04T22:59:48.000Z
    T790305  2112    1979-03-05T00:01:00.000Z  1979-03-05T23:59:47.000Z
    T790306  2068    1979-03-06T00:14:59.000Z  1979-03-07T00:14:44.000Z
    T790307  2068    1979-03-07T00:29:56.000Z  1979-03-07T23:59:56.000Z
    T790308  1848    1979-03-08T00:14:44.000Z  1979-03-08T23:59:08.000Z
    T790309  2112    1979-03-09T00:15:08.000Z  1979-03-10T00:14:44.000Z
    T790310  1980    1979-03-10T00:29:56.000Z  1979-03-10T23:59:56.000Z
    T790311  2112    1979-03-11T00:14:44.000Z  1979-03-12T00:14:44.000Z
    T790312  2068    1979-03-12T00:29:56.000Z  1979-03-12T23:59:32.000Z
    T790313  1980    1979-03-13T00:14:44.000Z  1979-03-13T23:29:56.000Z
    T790314  2024    1979-03-14T00:02:20.000Z  1979-03-14T23:59:32.000Z
    T790315  2112    1979-03-15T00:15:08.000Z  1979-03-16T00:14:44.000Z
    T790316  2068    1979-03-16T00:29:56.000Z  1979-03-16T23:44:44.000Z
    T790317  2112    1979-03-17T00:00:20.000Z  1979-03-17T23:55:08.000Z
    T790318  1936    1979-03-18T00:15:08.000Z  1979-03-18T23:44:44.000Z
    T790319  2156    1979-03-19T00:00:44.000Z  1979-03-20T00:14:20.000Z
    T790320  2112    1979-03-20T00:29:56.000Z  1979-03-21T00:14:20.000Z
    T790321  1980    1979-03-21T00:29:56.000Z  1979-03-21T23:59:32.000Z
    T790322  2024    1979-03-22T00:15:08.000Z  1979-03-22T23:44:44.000Z

Confidence Level Overview
  =========================
    At all times during this planetary encounter there exist data
    in this data set that can be rated with the highest confidence
    level.  However, some of the channels of data are contaminated
    by various kinds and various levels of contaminations.  It is
    therefore imperative, in using this data set, that the
    contamination tables within the catalog be examined.  Also, not
    all kinds of contamination have been fully documented.  When in
    doubt the data supplier must be contacted.

    Some channels are subject to serious contaminations, and many
    of these contaminations cannot be removed except with a region-
    by-region analysis, which has not been done for this data.
    Thus, to use this data it is absolutely vital that the
    contamination types ('CONTAMINATION_ID' , 'CONTAMINATION_DESC')
    and the levels of contamination ('DATA_QUALITY_ID'
    corresponding to the definitions 'DATA_QUALITY_DESC') be
    carefully examined for all regions of study.  A dead time
    correction procedure has been applied in an attempt to correct
    the linear effects of detector overdrive (pulse-pileup).  This
    procedure does not fix severely overdriven detectors.  A
    procedure is available for correcting Voyager 2 LECP electron
    contamination of low energy ion channels, but its effectiveness
    has been evaluated only for the Uranus data set.  Thus,
    corrections have been applied only to the Uranus data set.

    Also included with this data are one standard deviation
    statistical uncertainties for the directional data (sectors 1
    through 8 and an average) expressed as a percent. Unknown values are
    generally coded as such, however in some instances the value
    will read 'zero' when its status is unknown.

    An ancillary data file (SUMMARY.TAB) describes data confidence
    for the period covered in the data files.  This file provides
    the following information:

       parameter name               description
       ----------------------------------------------------------
       time                         time in the format
                                    yyyy-mm-ddThh:mm:ss.sssZ

       coverage                     percent coverage during hour

       sector_confidence_structure  this structure consists of two
                                    columns (contamination_id and
                                    data_quality_id) repeated 8 times
                                    (once each for sectors 1-8)

       contamination_id             contamination ID during hour for sector

       data_quality_id              data quality ID during hour for sector

    Also included with this data are one standard deviation
    statistical uncertainties for the directional data (sectors 1
    through 8) expressed as a percent.  Unknown values are
    generally coded as such, however in some instances the value
    will read 'zero' when its status is unknown.


    Contamination Desc
    ------------------
      -1: affected data is unrated with regard to contamination type
       0: affected data is uncontaminated by contamination type
       1: affected data is marginally contaminated by contamination
          type
       2: affected data is seriously contaminated by a contamination
          type, but the measurement is probably retrievable
       3: affected data is seriously contaminated by contamination
          type, and the retrievability of the measurement is
          questionable
       4: affected data is so contaminated by contamination type
          that the measurement cannot be retrieved


    Data Quality Desc
    -----------------
      1: Ion channels penetrating background. All ion channels are
         subject to background due to high energy particles that
         penetrate detector shielding. Channels that are the result
         of 'particle multiple parameters' measurements are less
         subject to such contamination (channels 'CH__'). A crude
         quality parameter has been derived from the ratio of the
         shielded and unshielded 53 to 85 keV 'pl01' ion channel.
         All other channels must be judged independently from
         context and from a corresponding ratio. No corrections
         have been applied.

      2: Solar UV. When the lowest energy ion and electron
         detectors (electron detector less affected) face the sun
         (sector 1) substantial background counts can occur in the
         lowest (pl01) and (somewhat) next to lowest (pl02) ion
         channels. A very crude quality parameter is derived from
         the ratio of the sun-facing and adjacent sector for the
         pl01 channel. This parameter should not be accepted as
         the last word but should be only used for guidance, and it
         can be misleading. Electrons must be judged separately. No
         corrections have been applied.

      3: Ion channel electron contamination. The lowest energy ion
         channels (pl01 through pl05) are subject to contamination
         from > 400 keV electrons which penetrate the magnetic
         shielding. This condition is well diagnosed on Voyager 2
         but not on Voyager 1. Context, corresponding Voyager 2
         measurements, and the correlation between moderate energy
         electron channels and these ion channels must be use to
         diagnose this condition for Voyager 1. A correction has
         been applied only to the Voyager 2 Uranus data.

      4: Ion detector overdrive. If the fluxes striking a detector
         is too high, the output of that detector becomes anomalous
         due to pulse pileup (linear effects) and baseline
         restoration (non-linear effects) problems. All detectors
         are subject to possible problems. A crude quality
         parameter has been derived based on the total rate
         striking the detector that measures the lowest energy ions
         (pl01-pl08). Pl01-5 are the channels most strongly affected,
         with the greatest effects occurring for the lowest energy
         channels. A dead-time correction procedure has been applied
         to the data to help alleviate the less severe problems.

      5: Detector noise. The detector/electronics noise for the
         lowest energy detectors (ions in particular) is not too
         far below the lowest energy discrimination levels. That
         noise can appear as background counts in the lowest energy
         channels if the detector noise increases as a result of
         the detector being overdriven, etc. The lowest
         discrimination can be adjusted by ground command to help
         alleviate this problem. A crude quality parameter has been
         derived based on reasonable/unreasonable ratios of the ion
         channels pl01 and pl02. This parameter should be used only
         as a rough guide and can be misleading. No correction has
         been applied.

      6: Electron channels penetrating background. All electron
         channels are subject to background due to high energy
         particles that penetrate detector shielding. A crude
         quality parameter has been derived based on the ratio of
         the shielded and unshielded 37 to 70 keV 'eb02' electron
         channel. All other channels must be judged independently
         from context and from a corresponding ratio. No correction
         has been applied.

      7: Electron detector overdrive. If the fluxes striking a
         detector is too high, the output of that detector becomes
         anomalous due to pulse pileup (linear effects) and
         baseline restoration (non-linear effects) problems. All
         detectors are subject to possible problems. A crude
         quality parameter has been derived based on the total rate
         striking the detector that measures the lowest energy
         electrons (eb01-eb05). The greatest effects occur for the
         lowest energy channels. A dead-time correction procedure
         has been applied to the data to help alleviate less severe
         problems.

      8: Miscellaneous bad data spikes. There are 'spikes' in the
         data processed for this instrument due to telemetry
         problems and other processing problems. Their are routines
         to eliminate these spikes, however, sometimes real events
         (fast changing) are also eliminated. We have chosen to
         leave the spikes in and to eliminate them when needed from
         context.