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

    This data set includes calibrated magnetic field data acquired by
    the Voyager 1 Low Field Magnetometer (LFM) during the Jupiter
    encounter. Coverage begins in the solar wind inbound to Jupiter and
    continues past the last outbound bowshock crossing. The data are in
    Heliographic (RTN) coordinates and have been averaged from the 60 ms
    instrument sample rate to a 1.92 second sample rate. All magnetic
    field measurements are given in nanoTesla (nT). The magnetic field
    data are calibrated (see the calibration description included in the
    Voyager 1 Magnetometer instrument catalog file for details).


    Parameters
    ==========

    The full LFM instrument sample rate is 1 sample per 0.06 seconds.
    Full telemetry resolution 'detail' data must be obtained from the
    instrument team. These data have been resampled at 1.92 seconds from
    the detail data.

    The LFM has eight dynamic ranges. The instrument is designed switch
    between dynamic ranges automatically depending upon the observed
    magnetic field magnitude and fluctuations. Instrument digitization
    uncertainty depends upon dynamic range as indicated in the following
    table (from [BEHANNONETAL1977]).

    -----------------------------------------------
    LFM Dynamic ranges and quantization uncertainty
    -----------------------------------------------
    Range (nT)               Quantization (nT)
    -----------------------------------------------
    1.  +/- 8.8                    +/- .0022
    2.  +/- 26                     +/- .0063
    3.  +/- 79                     +/- .019
    4.  +/- 240                    +/- .059
    5.  +/- 710                    +/- .173
    6.  +/- 2100                   +/- .513
    7.  +/- 6400                   +/- 1.56
    8.  +/- 50,000                 +/- 12.2


    Processing
    ==========

    Voyager EDR's undergo the following processing in order to produce
    these 1.92 second averaged summary data:

      * Read EDR
      * Unpack header block (rec. id, s/c id, tel. mode, FDS counts,
        data flags)
      * Convert selected time tags to integer time (yy/ddd/hh:mm:ss.fff)
      * Unpack sub-header block (MAG status words, plasma data)
      * Unpack science block (MAG counts)
      * Convert counts to gammas
      * Apply sensor and boom alignment matrices
      * Rotate (optional) 1.92 second averages while averaging detail
        gammas to create 1.92 second averages
      * Write Summary record

    Counts are measured onboard using 12 bit words that may represent
    values ranging from 0-4096. Integer counts are converted to magnetic
    field units (gammas) by subtracting a zero offset, from the measured
    MAG value and multiplying this difference by the sensitivity of the
    instrument.


    Data
    ====

    The data files are given in ASCII, fixed field width, comma
    delimited tables. The record structure is described in the following
    table:

    --------------------------------------------------------------------
    1.92 Second Heliographic (RTN) Coordinates
    --------------------------------------------------------------------
    Column   Type    Description 
    --------------------------------------------------------------------
    time     a23     spacecraft event time (UT) of the sample in the
                     format: yyyy-mm-ddThh:mm:ss.sss
    sclk     a12     spacecraft clock in the format:
                     MOD65536:MOD60:FDS-LINE
    mag_id   i1      magnetometer ID (1 = LFM, 2 = HFM)
    Br       f9.3    average of detail magnetic field R component in nT
    Bt       f9.3    average of detail magnetic field T component in nT
    Bn       f9.3    average of detail magnetic field N component in nT
    Bmag     f9.3    magnitude of the averaged magnetic field components
                     in nT
    avg_Bmag f9.3    average of the magnetic field magnitude over the
                     averaging interval in nT
    Delta    f7.3    spacecraft centered heliographic magnetic field
                     latitude in degrees: Delta = asin(Bn/Bmag)
    Lambda   f7.3    spacecraft centered heliographic magnetic field
                     longitude in degrees: Lambda = atan(Bt/Br)
    rms_Br   f8.3    root-mean-square deviation of Br over the averaging
                     interval in nT
    rms_Bt   f8.3    root-mean-square deviation of Bt over the averaging
                     interval in nT
    rms_Bn   f8.3    root-mean-square deviation of Bn over the averaging
                     interval in nT
    npts     i2      number of detail points in the average

    [Note that the magnetic field vector descriptions given above
    are best at lower latitudes, including all latitudes reached by
    Voyager during the Jupiter encounter]


    Ancillary Data
    ==============

    An ancillary data file containing the derived spacecraft magnetic
    field is provided with this data at a 48 second sample rate. These
    data provide zero level offsets used in the data processing.
    Spacecraft field data is provided in spacecraft coordinates as
    follows:

    --------------------------------------------------------------------
    48 Second Spacecraft Field (Payload) Averages
    --------------------------------------------------------------------
    Column   Type    Description 
    --------------------------------------------------------------------
    time     a23     spacecraft event time (UT) of the sample in the
                     format: yyyy-mm-ddThh:mm:ss.sss
    sclk     a12     spacecraft clock in the format:
                     MOD65536:MOD60:FDS-LINE
    mag_id   i1      magnetometer ID (1 = LFM, 2 = HFM)
    Bx       1pe10.3 average Bx spacecraft field in nT (payload coords.)
    By       1pe10.3 average By spacecraft field in nT (payload coords.)
    Bz       1pe10.3 average Bz spacecraft field in nT (payload coords.)
    Bmag     1pe10.3 magnitude of spacecraft field in nT
    rms_Bx   1pe10.3 root-mean-square deviation of Bx over the averaging
                     interval in nT
    rms_By   1pe10.3 root-mean-square deviation of By over the averaging
                     interval in nT
    rms_Bz   1pe10.3 root-mean-square deviation of Bz over the averaging
                     interval in nT
    npts     i4      number of points in the average


    Coordinate Systems
    ==================

    These data are provided in a heliographic right handed spherical
    coordinate system known as RTN. RTN coordinates are defined by the
    following directions:

      R - radial direction: along the Sun to spacecraft line, positive
          in the anti-Sunward direction
      T - tangetial direction: Omega (the Sun's spin axis) X R (parallel
          to the Solar Equatorial plane)
      N - normal direction: completes the right handed set


    References
    ==========

    [NESSETAL1979]        Ness, N.F., M.H. Acuna, R.P. Lepping, L.F.
                          Burlaga, K.W. Behannon, and F.M. Neubauer,
                          Magnetic Field Studies at Jupiter by
                          Voyager 1: Preliminary Results, Science, Vol.
                          204, p. 982, 1979.

    [LEPPINGETAL1981]     Lepping, R.P., L.F. Burlaga, L.W. Klein, J.
                          Jessen, and C.C. Goodrich, Observations of the
                          Magnetic Field and Plasma Flow in Jupiter's
                          Magnetosheath, J. Geophys. Res., Vol. 86,
                          p. 8141, 1981.

    [CONNERNEYETAL1981]   Connerney, J.E.P., M.H. Acuna, and N.F. Ness,
                          Modeling the Jovian Current Sheet and Inner
                          Magnetosphere, J. Geophys. Res., Vol. 86,
                          p. 8370, 1981.

    [BEHANNONETAL1981]    Behannon, K.W., L.F. Burlaga, and N.F. Ness,
                          The Jovian Magnetotail and Its Current Sheet,
                          J. Geophys. Res., Vol. 86, p. 8385, 1981.

Review
    ======

    These data have been reviewed by the instrument team and are of the
    highest quality that can be generated at this time. Science results
    based on these data have been published in several journals
    (Science, Nature, JGR, etc.). After submission to the PDS, these
    data successfully completed the peer review process.


    Data Coverage and Quality
    =========================

    ----------------------------------------------------
    Data File Coverage
    ----------------------------------------------------
    File        Start                Stop
    ----------------------------------------------------
    HG_1_92S_A  1979-02-26T00:00:35  1979-03-02T23:59:59
    HG_1_92S_B  1979-03-03T00:00:01  1979-03-16T23:59:58
    HG_1_92S_C  1979-03-17T00:00:00  1979-03-24T22:50:18

    These data originally included an 8-byte flag indicating software or
    spacecraft hardware intervention which reduced confidence in the
    data. However, these flags were provided only at a 48 second rate
    and are not included in this data set. To identify data confidence
    concerns in this data set please refer to the data flag provided in
    the 48 second data set. Data confidence conditions apply beginning
    at the record matching the time tag of the 48 second data and
    persist for 48 seconds (or 25 records in the 1.92 second data).