Data Set Description
      ====================

      Data Set Description
      --------------------
      This data set consists of resampled data from the Low Energy
      Charged Particle (LECP) experiment on Voyager 2 while the
      spacecraft was in the vicinity of Saturn. 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).

      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              : VG2
      Data Set Parameter Name         : ION RATE
      Instrument Parameter Name       : ION RATE
      Important Instrument Parameters : 1

      Instrument Host ID              : VG2
      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              : VG2-J-LECP-2-
      Software                        : PFAT:VGER
      Product Data Set ID             : VG2-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
-------------------------------------------------------------------
Volume ID: VG_1601
        SECTOR.TAB 14784  1981-08-24T00:00:00.000  1981-08-30T23:45:00.000
SECTOR_SUMMARY.TAB  1336  1981-08-24T00:00:00.000  1981-08-30T22:00:00.000

      Missing Data Flag
      =================
      Any data column whose value is -9.999e+10 missing data value.

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.

      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.