Voyager 2 Hourly Magnetic Field Data from 1977-1989

This data set contains hour averages of the interplanetary magnetic field (IMF) measurements obtained by the triaxial fluxgate magnetometer (MAG) 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 IMF 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. The X-HG axis is directed from the Sun to the spacecraft, Y-HG is the cross product of the solar rotation axis and X-HG, and Z-HG completes the orthogonal axis system. The accompanying format description file defines the transformation of the HG angles to vector components. Cartesian coordinates are given for the spacecraft in the sun-centered Inertial Heliographic (IHG) system, where the Z-IHG axis is parallel to the solar rotation axis, X-IHG points towards the ascending node direction of the solar equator's intersection with the Ecliptic, and Y-IHG is parallel to the solar equator and completes the orthogonal system. The MAG instruments are described by K. W. Behannon et al., Space Science Reviews, 21, 235, 1977. The data and coordinates are described by L. F. Burlaga, Space Science Reviews, 39, 255, 1984. These data are from 1977-1989 and include spacecraft position data whereas the 1990-2004 data do not. The seperation into two data products resulted from the fact that mean fields were falling towards the instrumentation digitization resolution. The Voyager/MAG team temporarily stopped production while they addressed the issue. Subsequent production in 1990 resulted in a similar data set, but without the spacecraft position. This data set is also related to the 1-hour merged Voyager mag and plasma data set. These associations are listed below using the SPASE AssociationID notation.