Data Set Information
DATA_SET_NAME VOYAGER 2 SOLAR WIND MAGNETIC FIELD HGCOORDS HOUR AVGS V1.0
DATA_SET_ID VG2-SW-MAG-4-SUMM-HGCOORDS-1HR-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview ================= This data set contains hour averages of the interplanetary magnetic field (IMF) measurements obtained by the triaxial fluxgate magnetometer experiment on Voyager 2. Identical instruments on Voyager 1 and 2 were designed to measure the IMF between Earth and Saturn (10 AU) during the primary Voyager mission. The design and performance yielded absolute accuracies to better than < 0.1 nT. In general, each component of the hourly average has an uncertainty of up to (+/- 0.05 nT) in the region beyond 10 AU. More accurate measurements can be obtained by special processing of the data, but it was not feasible to do this for the entire data set included here. The magnetic field magnitude in nT is provided along with angles of the field vector in the spacecraft- centered Heliographic (HG) coordinate system, also known as RTN. Coordinate System ================= Interplanetary magnetic field studies make use of two important coordinate systems, the Inertial Heliographic (IHG) coordinate system and the Heliographic (HG) coordinate system. The IHG coordinate system is use to define the spacecraft's position. The IHG system is defined with its origin at the Sun. There are three orthogonal axes, X(IHG), Y(IHG), and Z(IHG). The Z(IHG) axis points northward along the Sun's spin axis. The X(IHG) - Y(IHG) plane lays in the solar equatorial plane. The intersection of the solar equatorial plane with the ecliptic plane defines a line, the longitude of the ascending node, which is taken to be the X(IHG) axis. The X(IHG) axis drifts slowly with time, approximately one degree per 72 years. Magnetic field orientation is defined in relation to the spacecraft. Drawing a line from the Sun's center (IHG origin) to the spacecraft defines the X axis of the HG coordinate system. The HG coordinate system is defined with its origin centered at the spacecraft. Three orthogonal axes are defined, X(HG), Y(HG), and Z(HG). The X(HG) axis points radially away from the Sun and the Y(HG) axis is parallel to the solar equatorial plane and therefore parallel to the X(IHG)-Y(IHG) plane too. The Z(HG) axis is chosen to complete the orthonormal triad. An excellent reference guide with diagrams explaining the IHG and HG systems may be found in Space and Science Reviews, Volume 39 (1984), pages 255-316, MHD Processes in the Outer Heliosphere, L. F. Burlaga [BURLAGA1984]. Data Formats ============ field description (data before 1990) ----- ------------------------------ 1. s/c id (1 = Voyager-1, 2 = Voyager-2) 2. UTC YY DDD HH where YY=year, DDD=day, and HH=hour 3. X X IHG position component (A.U. - IHG coordinates) 4. Y Y IHG position component (A.U. - IHG coordinates) 5. Z Z IHG position component (A.U. - IHG coordinates) 6. Range Heliocentric range = sqrt(X*X+Y*Y+Z*Z) 7. F1 Field magnitude (nT) ( avg(F2(48sec)) ) 8. F2 Field modulus (nT) ( norm (B1,B2,B3) ) 9. delta Latitudinal angle (degrees - HG coordinates) 10. lambda Longitudinal angle (degrees - HG coordinates) field descriptor (data after 1990) ----- ---------------------------- 1. s/c identification (FLT1=Voyager 1) (FLT2=Voyager 2) 2. Time (UTC) decimal year format (90.00000 is day 1 of 1990) 3. The magnetic field strength, F1, computed from high-resolution observations. 4. The elevation angle (degrees) in heliographic coordinates. 5. The azimuthal angle (degrees) in heliographic coordinates. 6. The magnetic field strength, F2, computed from hour averages of the components. The components of B can be computed from F2 and the two angles. MAG field components may be recovered using F2, delta and lambda. BR = F2*COS(lambda)*COS(delta) Fortran users need to convert BT = F2*SIN(lambda)*COS(delta) degrees to radians before BN = F2*SIN(delta) using trig functions. Contact Information =================== Principal Investigator: Prof. Norman F. Ness Bartol Research Institute Univerity of Delaware Newark, Delaware 19716-4793 Phone: (302) 831-8116 Fax: (302) 831-1843 Email: norman.ness@mus.udel.edu Data Contact: Dr. Len Burlaga Code 612.2 NASA Goddard Space Flight Center Greenbelt, MD 20771 Tel.: 301-286-5956 Fax: 301-286-1433 E-mail: len.burlaga@nasa.gov References ========== Behannon, K.W., M.H. Acuna, L.F. Burlaga, R.P. Lepping, N.F. Ness, and F.M. Neubauer, Magnetic-Field Experiment for Voyager-1 and Voyager-2, Space Science Reviews, 21 (3), 235-257, 1977. Burlaga, L.F., Merged interaction regions and large-scale magnetic field fluctuations during 1991 - Voyager-2 observations, J. Geophys. Res., 99 (A10), 19341-19350, 1994. Burlaga, L.F., N.F. Ness, Y.-M. Wang, and N.R. Sheeley Jr., Heliospheric magnetic field strength and polarity from 1 to 81 AU during the ascending phase of solar cycle 23, J. Geophys. Res., 107 (A11), 1410, 2002. Ness, N., K.W. Behannon, R. Lepping, and K.H. Schatten, J. Geophys. Res., 76, 3564, 1971. Ness et al., 1973 Acknowledgement =============== Use of these data in publications should be accompanied at minimum by acknowledgements of the National Space Science Data Center and the responsible Principal Investigator defined in the experiment documentation provided here.
DATA_SET_RELEASE_DATE 2009-02-16T00:00:00.000Z
START_TIME 1977-09-05T12:00:00.000Z
STOP_TIME 2005-01-01T12:00:00.000Z
MISSION_NAME VOYAGER
MISSION_START_DATE 1972-07-01T12:00:00.000Z
MISSION_STOP_DATE N/A (ongoing)
TARGET_NAME SOLAR WIND
TARGET_TYPE
INSTRUMENT_HOST_ID VG1
INSTRUMENT_NAME DUAL TECHNIQUE MAGNETOMETER
TRIAXIAL FLUXGATE MAGNETOMETER
MAGNETOMETER
FLUXGATE MAGNETOMETER
INSTRUMENT_ID MAG
INSTRUMENT_TYPE MAGNETOMETER
Magnetometer
NODE_NAME planetary plasma interactions
ARCHIVE_STATUS ARCHIVED
CONFIDENCE_LEVEL_NOTE These data have been extracted from the NSSDC archive for distribution by the PDS along with other Voyager solar wind data sets. These data were not submitted to the PDS for archive and have not been through the PDS peer review process. These data are provided by the PDS for the convenience of PDS users. Please exercise caution when using these data. At the time of experiment proposal, it was expected that the required accuracy of the measurements would be 0.1 nT, determined by the combined noise of the sensors and the spacecraft field. The spacecraft magnetic field at the outboard magnetic field sensor, referred to as the primary unit, was expected to be 0.2 nT and highly variable, consistent with current estimates. Hence, the dual magnetometer design ([NESSETAL1971], [NESSETAL1973], [BEHANNONETAL1977]). At distances > 40 AU, the heliospheric magnetic fields are generally and 85 AU is about 0.15 nT and 0.05 nT, respectively. The use of roll zero levels for the two independent magnetic axes that are perpendicular to the roll axis (which is nearly parallel to the radius vector to the Sun) at intervals of about 3 months. There is no roll calibration for the third magnetic axis. Comparison of the two derived magnetic vectors from the two magnetometers permits validation of the primary magnetometer data with an accuracy of 0.02 to 0.05 nT. A discussion of the uncertainties that must be considered when using these data is given in the Appendix of Burlaga et al. [1994] and in Appendix A of [BURLAGAETAL2002]. The data beyond 40 AU (1990) are included in a separate file.
CITATION_DESCRIPTION Ness, N., VOYAGER 2 SOLAR WIND MAGNETIC FIELD HGCOORDS HOUR AVGS V1.0, VG2-SW-MAG-4-SUMM-HGCOORDS-1HR-V1.0, NASA Planetary Data System, 2009.
ABSTRACT_TEXT This dataset contains Voyager 2 magnetometer data from the interplanetary cruise averaged to 1 hour samples in Heliographic coordinates.
PRODUCER_FULL_NAME DR. LEN BURLAGA
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