Data Set Overview
  =================

    Version 1.1
    -----------
      This version 1.1 data set replaces the version 1.0 data set
      (DATA_SET_ID = VG1-J-PLS-5-ION-MOM-96.0SEC) previously
      archived with the PDS.


    Data Set Description
    --------------------
      This data set contains the best estimates of the total ion
      density at Jupiter during the Voyager 1 encounter in the PLS
      voltage range (10-5950 eV/Q).  It is calculated using the
      method of [MCNUTTETAL1981] which to first order consists of
      taking the total measured current and dividing by the
      collector area and plasma bulk velocity.  This method is only
      accurate for high mach number flows directly into the
      detector, and may result in underestimates of the total
      density of a factor of 2 in the outer magnetosphere.  Thus
      absolute densities should be treated with caution, but
      density variations in the data set can be trusted.  The low
      resolution mode density is used before 1979 63 1300, after
      this the larger of the high and low resolution mode densities
      in a 96 sec period is used since the L-mode spectra often are
      saturated.  Corotation is assumed inside L=17.5, and a
      constant velocity component of 200 km/s into the D cup is
      used outside of this.  These are the densities given in
      [MCNUTTETAL1981] corrected by a factor of 1.209 (.9617) for
      densities obtained from the side (main) sensor.  This
      correction is due to a better calculation of the effective
      area of the sensors.  Data format: column 1 is time
      (yyyy-mm-ddThh:mm:ss.sssZ), column 2 is the moment density in
      cm^-3.  Each row has format (a24, 1x, 1pe9.2).  Values of
      -9.99e+10 indicate that the parameter could not be obtained
      from the data using the standard analysis technique.
      Additional information about this data set and the instrument
      which produced it can be found elsewhere in this catalog.  An
      overview of the data in this data set can be found in
      [MCNUTTETAL1981] and a complete instrument description can be
      found in [BRIDGEETAL1977].

      Processing Level Id            : 5
      Software Flag                  : Y


  Parameters
  ==========

    Ion Density
    -----------
      Sampling Parameter Name        : TIME
      Data Set Parameter Name        : ION DENSITY
      Sampling Parameter Resolution  : 96.000000
      Sampling Parameter Interval    : 96.000000
      Minimum Available Sampling Int : 96.000000
      Data Set Parameter Unit        : EV
      Sampling Parameter Unit        : SECOND

      A derived parameter equaling the number of ions per unit
      volume over a specified range of ion energy, energy/charge,
      or energy/nucleon.  Discrimination with regard to mass and or
      charge state is necessary to obtain this quantity, however,
      mass and charge state are often assumed due to instrument
      limitations.

      Many different forms of ion density are derived.  Some are
      distinguished by their composition (N+, proton, ion, etc.) or
      their method of derivation (Maxwellian fit, method of
      moments).  In some cases, more than one type of density will
      be provided in a single data set.  In general, if more than
      one ion species is analyzed, either by moment or fit, a total
      density will be provided which is the sum of the ion
      densities.  If a plasma component does not have a Maxwellian
      distribution the actual distribution can be represented as
      the sum of several Maxwellians, in which case the density of
      each Maxwellian is given.


  Source Instrument Parameters
  ============================
    Instrument Host ID              : VG1
    Data Set Parameter Name         : ION DENSITY
    Instrument Parameter Name       : ION RATE
                                      ION CURRENT
                                      PARTICLE MULTIPLE PARAMETERS
    Important Instrument Parameters : 1 (for all parameters)


  Processing
  ==========

    Processing History
    ------------------
      Source Data Set ID          : VG1-PLS
      Software                    : MOMANAL
      Product Data Set ID         : VG1-J-PLS-5-ION-MOM-96.0SEC


    Software 'MOMANAL'
    ------------------
      Software Name               : MOMANAL
      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
    -------------------------------------------------------------------
    T790301  3792    1979-03-01T12:04:12.474Z  1979-03-05T16:45:54.608Z

Confidence Level Overview
  =========================
    This data set provides an estimate of the positive ion charge
    density.  Several assumption are made to simplify the analysis;
    these may affect the accuracy of the results.  High mach number
    flow is assumed; mach numbers of 2-3, which are reasonable
    lower limits for heavy ions, result in 10-20% underestimates of
    the charge density.  The analysis assumes a unit response (ie.,
    all particles in a cold beam incident on the aperture of the
    experiment would be measured at the collector).  The actual
    response is documented in [MCNUTTETAL1981] and can be as low as
    70%.  a velocity into the detector must also be assumed; the
    velocity used is the corotation velocity inside of 17.5 R[J]
    and 200 km/s outside of this.  This velocity profile is in
    accord with that measured where velocity determinations are
    possible, but the use of incorrect values give errors in the
    density which vary linearly with errors in the velocity.
    Finally, only ions in the PLS energy range (10-5950 eV/Q) are
    counted.  The cumulative error from all these effects is less
    than 10% in the solar wind, less than a factor of two in the
    outer magnetosphere (R>20 R[J]) and less than 20-30% inside of
    this.  Since the amplitude of each of these effects varies
    slowly in time (distance), the relative changes in density are
    good to a few percent in most cases.


  Missing Data Flag
  =================
    Any column whose value is -9.99e+10 is a bad or missing data
    value.