Data Set Summary ================ Data Set ID: VG1-J-MAG-4-RDR-S3COORDS-1.92SEC-V1.1 Instrument: MAG Instrument P.I.: Norman F. Ness Data Supplier: National Space Science Data Center Data sampling rate: 1.92 seconds Data Set Start time: 1979-03-03T00:00:35.978Z Data Set Stop time: 1979-03-17T00:00:42.265Z Data column descriptions ------------------------ time char_24 time in the format yyyy-mm-ddThh:mm:ss.sssZ ctime float_8 seconds since 1966-01-01 00:00:00.000Z m65536 integer_4 s/c clock mod 65536 mod60 integer_4 s/c clock mod 60 fds_line integer_4 s/c clock fds line mag_id integer_4 magnetometer ID Br float_4 radial (Jupiter to spacecraft) B-field component Btheta float_4 North/South (system III) B-field component, positive southward Bphi float_4 azimuthal (system III) B-field component, positive eastward Bmag float_4 magnitude of the averaged magnetic field components avg_Bmag float_4 average of the magnetic field magnitudes delta float_4 delta = arcsin(Btheta/Bmag) lambda float_4 lambda = 180. - atan(Bphi/-Br) rms_Br float_4 rms Br rms_Bt float_4 rms Bt rms_Bn float_4 rms Bp npts integer_4 number of data points in average dflag char_8 data flag Missing data flag value ----------------------- Any data column whose value is greater than 1.0e30 is a missing data value. Data Description ================ This data set includes Voyager 1 Jupiter encounter magnetometer data from the Low Field Magnetometer (LFM) resampled at a 1.92 second sample rate. Data coverage begins in the solar wind and continues until at least the first magnetopause crossing. The data are given in Jovicentric System III (1965) right handed coordinates. The data set is composed of 18 columns: 1) time - UT of the sample in the format yyyy-mm-ddThh:mm:ss.sssZ, 2) ctime - continuous time (decimal seconds since 1966-01-01T00:00:00.000), 3-5) m65536, mod60, and fds_line - spacecraft clock values, 6) mag_id - magnetometer id (1 = LFM, 2 = HFM), 7) Br - radial (Jupiter to spacecraft) B-field component, 8) Btheta - North/South (system III) B-field component (positive southward), 9) Bphi - azimuthal (system III) B-field component (positive eastward), 10) Bmag - magnitude of the averaged magnetic field components, 11) avg_Bmag - average of the magnetic field magnitudes, 12) delta - magnetic latitude = arcsin(Btheta/Bmag), 13) lambda - longitude = 180. - atan(Bphi/-Br), 14-16) rms_br, rms_bt, and rms_bn - rms vectors 17) npts - number of points in average, 18) data flag - a flag value that indicates either software error or spacecraft hardware interference reduced confidence in this record (flag value of 1 is bad , 0 is good or unchecked). All magnetic field observations are measured in nanoTesla. The coordinate system for this data set is System (1965) III. All of the magnetic field data are calibrated (see the instrument calibration description for more details). The Jupiter System III coordinate system is defined in [DESSLER1983] and the reference documents for this data set are: [NESSETAL1979], [LEPPINGETAL1981], [CONNERNEYETAL1981], [BEHANNONETAL1981]. These data a provided in a conventional, right handed, spherical coordinate system with vectors R, Theta, and Phi. This system is sometimes referred to as System III (1965) right handed coordinates. The the magnetic field vectors are: BR - radial B-field component (along the Jupiter to spacecraft line) positive away from Jupiter BTHETA - North/South (system III) B-field component, positive southward BPHI - azimuthal (system III) B-field component, positive eastward Processing Level Id : 4 Software Flag : Y Processing Start Time : 1988-09-21 Parameters ---------- Sampling Parameter Name : TIME Data Set Parameter Name : MAGNETIC FIELD VECTOR Sampling Parameter Resolution : 1.920000 Minimum Sampling Parameter : 1.920000 Maximum Sampling Parameter : UNK Sampling Parameter Interval : 1.920000 Minimum Available Sampling Int : 0.060000 Data Set Parameter Unit : NANOTESLA Noise Level : 0.006000 Sampling Parameter Unit : SECOND PARAMETER RESOLUTION DESCRIPTION NAME (UNITS) time 1.92 Sec time of the sample (UT) in the format yyyy-mm-ddThh:mm:ss.sssZ. The full sampling rate for the instrument is .06 +/- .006 sec. ctime 1.92 Sec time provided in seconds since 1966-01-01T00:00:00.000Z without accounting for leap seconds m65536, (counts) s/c clock mod 65536, mod 60 and mod60 and fds line fds_line mag_id n/a magnetometer ID magnetic (nT) measured parameter equaling the field magnetic field strength (e.g. in components nanoTeslas) along a particular axis (Br, Btheta, direction. Usually the three Bphi) orthogonal axis components are measured by three different sensors. magnetic (nT) derived parameter which combines the 3 field vector orthogonal magnetic field component (Bmag, avg_Bmag) measurements. delta n/a delta = arcsin(Btheta/Bmag) lambda n/a lambda = 180. - atan(Bphi/-Br) rms_Br, Pythagorean root mean square deviation rms_Bt, and of the component averages rms_Bp npts (counts) the number of data points in the current average dflag n/a a character string which indicates software or s/c hardware intervention which reduces confidence in the data (NULL flags represent 'good' data) Source Instrument Parameters ---------------------------- Instrument Host ID : VG1 Data Set Parameter Name : MAGNETIC FIELD VECTOR Instrument Parameter Name : MAGNETIC FIELD COMPONENT Important Instrument Parameters : 1 Instrument Host ID : VG1 Data Set Parameter Name : MAGNETIC FIELD VECTOR Instrument Parameter Name : WAVE MAGNETIC FIELD INTENSITY Important Instrument Parameters : 1 Processing ---------- Processing History ------------------ Source Data Set ID : N/A Software : UNK Product Data Set ID : VG1-J-MAG-4-1.92SEC 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. S/C field data is provided in spacecraft coordinates as follows: PARAMETER RESOLUTION DESCRIPTION NAME (UNITS) time 48 sec time in format yyyy-mm-ddThh:mm:ss.sssZ m65536 n/a s/c clock mod 65536 mod60 n/a s/c clock mod60 mag_id n/a magnetometer ID Bx (nT) spacecraft coords. X component By (nT) spacecraft coords. Y component Bz (nT) spacecraft coords. Z component Bmag (nT) total magnetic field strength rms_Bx (nT) rms Bx component rms_By (nT) rms By component rms_Bz (nT) rms Bz component npts (counts) number of points in average Confidence Level Overview ------------------------- This data set contains some data gaps and spikes. The data set does contain a flag value which has been provided by the PI (Norman Ness) that indicates whether or not a particular record has been contaminated by software error or by spacecraft interference (a flag value of 1 indicates a bad value, 0 indicates that the record has either not been evaluated or is good). Some records that are obviously contaminated have not been flagged. The hourly summary data will show a contamination code and data quality code of 2 when data in the hour have not been flagged but are obviously in error and a contamination code of 1 when the hour contains flagged records.