Data Set Overview : This data set contains magnetic-field data acquired during the cruise and tour phases of the Cassini mission to Saturn. On 16 August, 1999 two days before the spacecraft commenced Earth swingby, the magnetometer boom was unfurled into its extended position; a configuration it maintained for the remainder of the mission. Magnetic-field data acquired prior to boom deployment are limited and are significantly affected by spacecraft noise. These data are of no scientific value and, consequently, do not form part of this data set. Cassini carried two magnetometers: a fluxgate magnetometer (FGM) and a vector-helium magnetometer capable of operating in both vector and scalar mode (V/SHM). This data set contains calibrated, and averaged magnetic-field data recorded by the FGM instrument. The data are provided in 1 minute averages. The 1 minute data are provided in year files. The data are provided in RTN coordinates throughout the mission. After arrival at Saturn, the Saturn-centered KRTP, KSO, and KSM coordinates are also provided. Earth-centered, and Jupiter-centered coordinates are provided for the flybys of those two planets. All data files are ASCII. These data were calibrated, and rotated into geophysical coordinates by the Cassini MAG team at Imperial College (IC), and provided to the PDS/PPI node via the Cassini MAG team Co-I at UCLA. In other words these data use the same calibration as the data routinely delivered to the Cassini MAG team. The data were also averaged at IC. The data were reformatted into their current ASCII format, add trajectory information was added at PDS/PPI. Processing : Coordinate Systems : The coordinate systems in which the data are provided in vary by mission phase, and are designed to support both solar wind and planetary magnetospheric studies. Solar Wind Coordinates ---------------------- Radial-Tangential-Normal Coordinates (RTN) ------------------------------------------ RTN coordinates consist of R (radial component, Sun to the spacecraft), T (tangential component, parallel to the Solar Equatorial plane and perpendicular to R), and N (normal component, completes right handed set). Saturn-Centered Coordinates --------------------------- Kronocentric body-fixed, J2000 spherical Coordinates (KRTP) ----------------------------------------------------------- KRTP magnetic field vector components form the standard right-handed spherical triad (R, Theta, Phi) for a planet-centered system. Namely, R is radial (along the line from the center of Saturn to the center of the spacecraft), and positive away from Saturn. Phi, the azimuthal component, is parallel to the Kronographic equator (Omega x R) and positive in the direction of corotation. Theta, the 'southward' component, completes the right-handed set. Kronocentric Solar Magnetospheric Coordinates (KSM) --------------------------------------------------- KSM is a cartesian Saturn-center coordinate system where X points from Saturn to the Sun, the X-Z plane contains Saturn's centered magnetic dipole axis, M, and Y completes right handed set. Kronocentric Solar Orbital Coordinates (KSO) -------------------------------------------- KSO is a cartesian Saturn-centered coordinate system where X points from Saturn to the Sun, Z is parallel to Saturn's orbital plane upward normal, and Y completes the right handed set. Earth-Centered Coordinates -------------------------- Jupiter-Centered Coordinates ---------------------------- Jovicentric Body-Fixed (IAU_JUPITER) Coordinates (J3) ----------------------------------------------------- J3 is a body-fixed Jovicentric cartesian coordinate system consistent with the IAU 1997 definition of the System 3 prime meridian where X is in the Jovian equatorial plane, along S3 1997 Prime Meridian, Z is parallel to the Jovian spin axis, and Y completes right-handed set. Jovicentric Body-Fixed Magnetospheric Coordinates (JMXYZ) --------------------------------------------------------- JMAG XYZ is a body-fixed Jovicentric cartesian coordinate system where X is in the plane containing Z and the S3 1997 Prime Meridian, Z is the Jupiter magnetic dipole, and Y completes right handed set. SPICE : The data product labels associated with the data set include the name of a SPICE metakerenls which contains a list of the SPICE kernels that were used in calibrating the magnetic-field data, coverting them to physical coordinates, and generating the associated trajectory information. Copies of these metakernels are included in the GEOMETRY directory of the archive volume on which the data are located. While the SPICE kernels themselves are not part of this data set, they are archived at the PDS-NAIF node on the volume cosp_1000. Note that the SPICE kernels listed in the metakernels may be uniquely identified by their file name.

Product Versions : PRODUCT_VERSION_ID 1 data were calibrated at the PDS/PPI node at UCLA using software (CAL02), and calibration data provided by the Cassini MAG team. The process used the same calibration data that was provided with the Raw Magnetometer data archive (Data Set ID: CO-E/SW/J/S-MAG-2-REDR-RAW-DATA-V1.0). The data were then rotated into geophysical coordinates using MAG team additonal MAG team provided code (TRANSCAL) and spice kernels obtained from NAIF. Additional processing, including averaging, reformatting to ASCII, and the addition of trajectory to the 1 minute data was performed using code developed at PDS/PPI. PRODUCT_VERSION_ID 2 data were calibrated, and rotated into geophysical coordinates by the Cassini MAG team at Imperial College, and provided to the PDS/PPI node via the MAG team Co-I at UCLA. The 1 minute data were also averaged at IC. Averaging for the 1 second data was performed at PDS/PPI. The data were reformatted at PDS/PPI to match the format used for the version 1 data. PRODUCT_VERSION_ID 3 data were processed following the same procedure that was followed for the version 2 data. However, subsequent to the release of the version 2 data it was discovered that the coordinate system trasformation for some of those data had been performed using predict SPICE kernels, rather than reconstructions. The version 3 were reprocessed using reconstructed ephemeris kernels for all of the data. PRODUCT_VERSION_ID 4 data were processed following the same procedure that was followed for the version 2 and 3 data. These data, however, were processed using only reconstructed SPK's to generate the trajectory data, thus correcting the errors which were present in the version 3 data. The MAG data do not differ between versions 3 and 4. PRODUCT_VERSION_ID 5 data were processed following the same procedure that was followed for the version 3 and 4 data. These data include corrections to the NPTS column data values, and some updates to the label files. PRODUCT_VERSION_ID 6 for RTN data files - The DATA/ *_FGM_RTN_1M.TAB files, Version 5, and older versions, had assigned a width to the Sun to Spacecraft distance column (RANGE) that was insufficient to accommodate values over 10 AU. This resulted in inconsistent record structures and lengths. The version 6 RTN files correct this error by allocating an additional byte to the RANGE column width and adjusting the start position of the subsequent columns accordingly.