(Planetary Solar Ecliptic, Planet centered X=Sun, V2=Orbital normal)
    X      - Along the Planet->Sun line (S), positive towards the Sun.
    Y      - V2 x X
    Z      - Parallel to the Planetary orbital plane upward normal.

    (Planetary Solar Equatorial, Planet centered Z=Omega, V2=Planet-Sun vector)
    X      - In the Planet->Sun plane, positive towards the Sun.
    Y      - Z x X
    Z      - Northward spin axis of the Planet.

       KSM - This coordinate system will be similar to the GSM
    (Geocentric Solar Magnetospheric) coordinate system used at
    Earth.  Because Saturn's rotation axis and magnetic dipole
    axis are < 1 degree different, we will not differentiate them
    when defining this coordinate system.

          X = S (where S is the unit vector from Saturn to the Sun)
          Y = K x X (where K is the unit vector of the rotation axis)
          Z = X x Y

       The geographic coordinate system is defined so that its
    x-axis is in the planet's equatorial plane, but is fixed with
    the rotation of the planet, so that it passes through the prime
    meridian.  Its z-axis is parallel to the rotation axis of the
    planet, and its y-axis completes a right-handed orthogonal set.
    The centrifugal latitude ("CentLat") is computed using the method
    described in https://doi.org/10.1029/2020JA028713.

    PhiO (Satellite centered inertial Phi-Omega coordinates)
    [Co-rotational coordinate system]

       The X-direction is defined to be in the direction of corotation,
    at the center of the satellite (System III Phi direction [DESSLER1983]).
    The Z-axis is defined to be orthogonal to the X direction such that the
    X-Z plane contains the Jupiter spin axis (Omega), positive in the direction
    of angular momentum. The Y-axis is defined to complete the right-handed
    set.  Since the major jovian satellites all lie very close to the jovian
    equatorial plane, it is often convenient to visualize this coordinate
    system as follows:  X lies in the direction of plasma flow, Y points
    towards Jupiter, and Z points 'up'.