  Semi-Lagrangian solvers for the Vlasov system offer noiseless solutions
compared to Lagrangian particle methods and can handle larger time steps
compared to Eulerian methods. In order to reduce the computational complexity
of the interpolation steps, it is common to use a directional splitting.
However, this typically yields the wrong angular velocity. In this paper, we
analyze a semi-Lagrangian method that treats the $v \times B$ term with a
rotational grid and combines this with a directional splitting for the
remaining terms. We analyze the convergence properties of the scheme both
analytically and numerically. The favorable numerical properties of the
rotating grid solution are demonstrated for the case of ion Bernstein waves.
