Distribution of the centroid positions of various velocity channels of the 7₁–6₁-A, ν_t = 0 (bottom) and 12_-1–12₀-A, ν_t = 0 (top) lines. In both panels, the velocity of the most blue- and red-shifted channels are subtracted by the systemic velocity. The velocity channels close to systemic velocity are marked in green. The arrows indicate the direction of the SiO jet; the dashed line traces the equatorial plane.