Contour levels of the upper limits for the errors in the polarization degree σ_Π (left) and in the orientation angle σ_ψ (in degrees, right), caused by a positioning error σ_θ, versus the values of the Stokes parameters S₁ and S₂ normalized to S₀. The figure refers to N = 8. The thick contours identify the normalized values of S₁ and S₂ for which Π is, from bottom left to top right, 3%, 5%, and 10%.