Dependence on the inclination angle, α, of the theoretical expression for , given by Eq. (A.13), for θ_P → θ_PS, σ₂₁ → 0, and τ → τ_2min → τ_2max, shown by the red points. The theoretical value of ranges from infinity to zero over the interval 0 < α ≤ π/2. The horizontal dashed line (in blue) shows the value of , given by Eq. (A.12), for the parameters of the Crab Pulsar derived from observations. As indicated by the vertical dashed line (in blue), these two values of match for an α = 1.32 radian (i.e. α = 75.5°).