NASA Logo, National Aeronautics and Space Administration
NASA Space Science Data Coordinated Archive Header

VG1 JUP MAG RESAMPLED HELIOGRAPHIC (RTN) COORDS 9.60SEC V1.0 (PDS)

NSSDCA ID: PSFP-00494

Availability: Archived at NSSDC, accessible from elsewhere

Time span: 1979-02-26 to 1979-03-24

Description

This description was generated automatically using input from the Planetary Data System.

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 1.92 second summary data to a 9.6 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. For this data set, the data have been resampled to 9.6 seconds from 1.92 second summary data. The 1.92 second data were in turn resampled 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 9.6 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 * Average 1.92 second data to 9.6 seconds * 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: -------------------------------------------------------------------9.6 Second Heliographic (RTN) Coordinates -------------------------------------------------------------------Column Type Description <units> ------------------------------------------------------------------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 <units> -------------------------------------------------------------------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.

These data are available on-line from the Planetary Data System (PDS) at:

https://pds-ppi.igpp.ucla.edu/data/VG1-J-MAG-4-SUMM-HGCOORDS-9.60SEC-V1.0/

Alternate Names

  • VG1-J-MAG-4-SUMM-HGCOORDS-9.60SEC-V1.0

Discipline

  • Planetary Science: Fields and Particles

Additional Information

Spacecraft

Experiments

Questions and comments about this data collection can be directed to: Dr. Edwin V. Bell, II

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. Norman F. NessData ProviderUniversity of Delawarenfness@bartol.udel.edu
[USA.gov] NASA Logo - nasa.gov