Distribution of the centroid positions of various velocity channels of the 7₁–6₁-A, ν_t = 0 line (squares) and of the C¹⁷O(2–1) transition (crosses). Velocities are colour-coded according to the scale shown in the figure and are subtracted by the systemic velocity. The arrows indicate the direction of the jet; the dashed line traces the equatorial plane. For clarity, the C¹⁷O(2–1) velocity channels are connected by dotted lines. The dotted ellipse represents the elliptical Gaussian fit to the averaged visibilities of the 7₁–6₁-A, ν_t = 0 line.