Rotation period of Jupiter from the observation of its magnetic field

To determine the Jovian internal rotation rate, historically one has used the repetition period (periodicity) of decametric and decimetric radio waves. The period with which decametric and decimetric radio waves recur on Jupiter (the System III period) was defined by the IAU in 1965 to be 9h 55m 29.71s, based on early radio astronomical data. A more direct way to determine this period is to examine the rotation rate of the dipole field. We have done this using Galileo, Pioneer 10 and 11, Voyager 1 and 2, and Ulysses data over a 25-year period. We find a small drift in the apparent longitude of the dipole axis that is statistically significant, consistent with there being a small error in the original IAU period, one within the error expected in the defined period. The newly derived period is 9h 55m 29.704 +/- 0.003s, 6ms shorter than the 1965 IAU definition, and inconsistent with the value of 9h 55m 29.685s proposed by Higgins et al. (1997). Citation: Yu, Z. J., and C. T. Russell (2009), Rotation period of Jupiter from the observation of its magnetic field, Geophys. Res. Lett., 36, L20202, doi:10.1029/2009GL040094.