The phase ∠β₂ as a function of observed impact parameter b in an equatorial monopole model viewed face-on from the south pole (θ_o = π). For several values of the black hole spin a_* ∈ {0.1, 0.5, 0.9, 0.99}, we plot ∠β₂ for models over a range of field-line angular velocities parameterized by w = Ω_F/Ω_H. The shaded regions show the full range of ∠β₂ over 1/4 ≤ w ≤ 3/4, while the solid lines show the models with w = 1/2. Dashed lines indicate the observed ∠β₂ from a flat-space monopole with w = 1/2. Solid dots at the left end of each curve show the horizon value of ∠β₂ (Equation (36)) for face-on equatorial emission.