“Observed” rotation curve V_ϕ,obs(r) obtained from the difference of peak velocity between ± r from the jet axis (Eq. (16)) for our reference model viewed at i = 40°, 60°, 70°, and 80° (color-coded curves). (a): Spatially resolved regime (θ_b = 45 au), (b): spatially unresolved regime (θ_b = 225 au; we note the change of scales on both axes). In both panels, a vertical black line indicates the beam FWHM, and colored vertical dashed lines indicate the flow radius r_j at z_cut = 225 au. The true wind rotation curve V_ϕ(r) at z = z_cut∕sin i) is shown by dotted curves, with a constant value beyond r_j. The cross on the red curve illustrates where the local intensity drops below 10% of the PV peak.