Left panels: the points show the [Oiii]λ5007 velocity v versus the distance R of the [Oiii]λ5007 photocentre from the continuum (indicated by the dashed line). The arrows indicate the velocity v_o = v(R_o) corresponding to the distance R₀. Right panels: [Oiii]λ5007 photocentre position in the field of view. Symbols are coloured according to their velocity (the velocity scale is reported in the colour bar). The dotted line indicates the project direction of the outflow as inferred by comparing the spectroastrometry results with velocity maps (Fig. 3).