Geometrical configuration of a spinning and wobbling prolate spheroidal grain with notation by Das et al. (2010). The major axis O₁O₂ of the particle spheroid is placed in the spinning plane NO₁O₂ that is perpendicular to the angular momentum J. Direction of the light propagation k is set parallel to the Z-axis. We measure from Z the angle 0 ≤ Ω ≤ 90° to the magnetic field B, the angle α to the major rotation axis of the particle, and the angle θ to the angular momentum J; ϕ is the spin angle, β the precession-cone angle, and ω the current precession angle.