Magnetic excitation moments for large moons of the giant planets

Text files containing the spatially uniform (degree-1) magnetic oscillations experienced by each large moon of the giant planets as a function of frequency, also known as the excitation moments. All moments are in complex notation relative to the J2000 epoch. Used for determining the strength of induced magnetic fields from the moons from an interior conductivity structure. This dataset is compatible for use with the MoonMag and PlanetProfile frameworks for calculating induced magnetic fields of target moons. Refer to the publication linked below for more information.

All vector components are in IAU coordinates, such that at the body center, +z is directed along the body spin axis, +x is directed approximately toward the parent planet in the plane of an IAU-defined meridian feature, and +y is directed approximately opposite to the orbital velocity to complete the right-handed set. For the uranian moons and Triton, the IAU +z axes are opposite the spin axes because of their angles relative to the solar system invariable plane; the +y axes for these bodies are therefore directed approximately along the orbital velocity vector.

Excitation fields are determined by evaluation of SPICE kernels over a time series at the location of the body center. Position information is inserted into a magnetospheric model for the parent planet and complex Fourier coefficients are inverted from the time series using linear least squares optimization. The magnetic field models we use for each planet are:

• Jupiter - JRM33 + C2020 current sheet (Connerney et al., 2022, 2020) except Callisto, for which we use VIP4+K (Connerney et al., 1998; Khurana, 1997)
• Saturn - Cassini 11+ (Cao et al., 2020)
• Uranus - AH₅ (Herbert, 2009)
• Neptune - O8 (Connerney et al., 1991)

ASCII text files are included for all major moons of these planets.