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NASA Space Science Data Coordinated Archive Header



Availability: Archived at NSSDC, accessible from elsewhere

Time span: 1992-11-03 to 1992-12-19


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

Data Set Overview ================= This dataset contains data acquired by the Galileo Magnetometer from the Earth 2 encounter. The data have benn averaged down to twenty second resolution from the 7.68 kB Low Rate Science (LRS) real time telemetry mode. These data have been fully processed to remove instrument response function characteristics and interference from magnetic sources aboard the spacecraft. The data are provided in both Geocentric Solar Ecliptic (GSE) and Geocentric Solar Magnetic (GSM) coordinates. Trajectory data has been attached to this data for easier use. Trajectory data which was at a sample rate of once per minute, was linearly interpolated to match the 20 second sample rate of this data. Primary Reference: [KIVELSONETAL1993] Data ==== ----------------------------------------------------------------Table 1. Data record structure ----------------------------------------------------------------Column type description ----------------------------------------------------------------time char S/C event time (UT) in PDS time format: yyyy-mm-ddThh:mm:ss.sssZ Bx float X component GSE or GSM coords. (20s res) <nT> By_gse float Y component GSE coordinates (20s res) <nT> Bz_gse float Z component GSE coordinates (20s res) <nT> By_gsm float Y component GSM coordinates (20s res) <nT> Bz_gsm float Z component GSM coordinates (20s res) <nT> Bmag float |B| Magnitude of B (20s res) <nT> stBx float Standard deviation for: Bx <nT> stBy_gse float Standard deviation for: By_gse <nT> stBz_gse float Standard deviation for: Bz_gse <nT> stBy_gsm float Standard deviation for: By_gsm <nT> stBz_gsm float Standard deviation for: Bz_gsm <nT> stBmag float Standard deviation for: Bmag <nT> npts int Points in average dqf int Data quality flag X float X component GSE and GSM <Re = 6378 km> Y_gse float Y component GSE coordinates <Re> Z_gse float Z component GSE coordinates <Re> Y_gsm float Y component GSM coordinates <Re> Z_gsm float Z component GSM coordinates <Re> Data Acquisition: The data for this dataset were acquired as part of the normal instrument calibration activities associated with the cruise to Jupiter. As such, the instrument was commonly configured in modes which required calibration even though they may not have been the optimal mode for science data acquisition. The Galileo magnetometer has 8 possible LRS acquisition configurations (modes). There are two sensor triads mounted 7 and 11 meters from the rotor spin axis (inboard and outboard) along the boom. Each of the sensor triads has two gain states (high and low). In addition, the sensor triads can be 'flipped' to move the spacecraft spin-axis aligned sensor into the spin plane and visa versa. Please see the instrument description for full details on the instrument, sensors, and geometries. The combinations of sensor, gain state, and flip direction form modes. -----------------------------------------------------------------Table 2. Mode Characteristics -----------------------------------------------------------------Mode Name Acronym range quantization -----------------------------------------------------------------Inboard, left, high range* ILHR +/- 16384 nT 8.0 nT Inboard, right, high range* IRHR +/- 16384 nT 8.0 nT Inboard, left, low range* ILLR +/- 512 nT 0.25 nT Inboard, right, low range* IRLR +/- 512 nT 0.25 nT Outboard, left, high range* ULHR +/- 512 nT 0.25 nT Outboard, right, high range* URHR +/- 512 nT 0.25 nT Outboard, left, low range* ULLR +/- 32 nT 0.008 nT Outboard, right, low range* URLR +/- 32 nT 0.008 nT -----------------------------------------Table 3. Mode change history -----------------------------------------s/c clock date/time mode -----------------------------------------* range is the opposite of gain In addition to exercising the various instrument modes during the first earth encounter, numerous instrument calibration activities were performed. These include using both the internal and external calibration coils. Data corrupted by the use of the calibration coils or by the flipper motor have been removed from the processed data. These data have been archived with the Experimenter Data Records (EDR) and other Magnetometer team raw data archive products. Data Sampling: These data have been resampled to 20 seconds using overlapping 40 second averages of the high-resolution (~2/3 second) data. The time tag represents the center of the averaging interval. For a discussion regarding the high-resolution data please refer to the catalog file for the GO-E-MAG-3-RDR-E2-HIGHRES-V1.0 data set (/CATALOG/MAG_E2_HIGHRES_DS.CAT). Coordinate Systems ================== Geocentric Solar Ecliptic (GSE) and Geocentric Solar Magnetic (GSM) are related earth centered coordinate systems. Both the GSE and GSM X directions are taken along the Earth - Sun line, positive towards the Sun. The GSE Z direction is parallel to the ecliptic normal, positive northward, and Y completes the right-handed set (towards dusk). For GSM, the X-Z plane contains the Earth's dipole moment vector, positive northward, and Y completes the right-handed set. GSE coordinates are commonly used for analyzing the solar wind near the Earth and GSM coordinates are used when analyzing data inside the Earth's bow shock. Data Processing =============== These data have been processed from the PDS dataset: 'GO-E/V/A-MAG-3-RDR-HIRES-V1.0' In order to generate the IRC processed dataset, the following procedure was followed: 1) Sensor zero level corrections were subtracted from the raw data, 2) Data were converted to nanoTesla, 3) A coupling matrix which orthogonalizes the data and corrects for gains was applied to the data (calibration applied), 4) Magnetic sources associated with the spacecraft were subtracted from the data, 5) Data were 'despun' into inertial rotor coordinates, Lastly, in order to generate the processed data in GSE/GSM coordinates the data were transformed into geophysical coordinates and averaged to twenty second resolution. For a more detailed description of these proceedures please refer to the file /CALIB/HR_PROC.TXT. For more information regarding data calibration please refer to [KEPKOETAL1996].

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

Alternate Names



  • Planetary Science: Fields and Particles

Additional Information



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



NameRoleOriginal AffiliationE-mail
Dr. Margaret Galland KivelsonData ProviderUniversity of California, Los
Dr. Margaret Galland KivelsonGeneral ContactUniversity of California, Los
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