Top panel: polarization angles computed for the spherical (dashed) and the oblate (solid) star as a function of the rotation phase ϕ for different spot co-latitudes θ = 15° (red), 30° (green), 45° (blue), and 60° (purple). Second panel: relativistic rotation for the spherical (dashed) and the oblate (solid) stars. Third panel: component χ₁ for the oblate star. Bottom panel: difference between the PAs for the oblate and spherical stars. Parameters of the non-rotating NS are R₀ = 12 km and M₀ = 1.4 M_⊙, while in the oblate case of a NS rotating at a rate of ν_* = 600 Hz, the mass and radius are computed according to Eqs. (6) and (5). The inclination is i = 40°.