  The dynamics of a charged relativistic particle in electromagnetic field of a
rotating magnetized celestial body with the magnetic axis inclined to the axis
of rotation is studied. The covariant Lagrangian function in the rotating
reference frame is found. Effective potential energy is defined on the base of
the first integral of motion. The structure of the equipotential surfaces for a
relativistic charged particle is studied and depicted for different values of
the dipole moment. It is shown that there are trapping regions for the
particles of definite energies.
