Voyager 1 48-s Triaxial Fluxgate Magnetometer (MAG) Magnetic Field Data Near and Beyond Termination Shock in CDF Format

The main science objectives for the Voyager Interplanetary Mission, VIM, are as follows: - investigate the structure of the solar wind magnetic fields and plasma in the inner and outer heliosphere; - conduct long term study of heliospheric evolution during different phases of the 22-year solar magnetic cycle and the 11-year solar activity cycle; - study the long term solar modulation and determine the elemental and isotopic abundances of galactic cosmic ray particles in the heliosphere; - measure radial gradients, spectra, and nuclear abundances of the anomalous component of cosmic rays from acceleration at the solar wind termination shock; - investigate local particle acceleration in the interplanetary medium from solar flare shocks and corotating interaction regions; - study propagation of solar energetic particles in the heliosphere. The average magnetic field strength produced by the spacecraft at the location of the outboard magnetometer of the dual magnetometers system on Voyager 1 and Voyager 2 is about 0.1-0.2 nT, comparable to the most probable magnetic field strength in the inner heliosheath and significantly larger than the most probable magnetic field strength in the distant supersonic solar wind. The spacecraft magnetic field is a complex, time-dependent signal that must be removed from the measured magnetic field signal in order to derive the ambient magnetic fields of the solar wind and heliosheath. Corrections must also be made for spurious magnetic signals and noise associated with the telemetry system, ground tracking systems, and other factors. Extracting the signal describing the solar wind and heliosheath from the many sources of uncertainty is a complex and partly subjective process that requires understanding of the instrument and judgement based on experience in dealing with the ever-changing extraneous signals. We estimate that for the Voyager magnetic field data the 1-sigma the uncertainty of the 48-s averages for each of the components of the magnetic field BR, BT, and BN is typically +/- 0.02 nT; the uncertainty in magnitude F1 is typically +/- 0.03 nT. F1, BR, BT, and BN can differ from one another and they may vary with time, but there is no practical way to determine these uncertainties more precisely at present. References: D.B. Berdichevsky, Voyager Mission, Detailed processing of weak magnetic fields; I - Constraints to the uncertainties of the calibrated magnetic field signal in the Voyager missions, 2009; https://vgrmag.gsfc.nasa.gov/Berdichevsky-VOY_sensor_opu090518.pdf 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., Spacecraft studies of the interplanetary magnetic field, 76, 3564, 1971.

Tags: magneticfield
Organization: National Aeronautics and Space Administration