Colour scale in the central panel shows the SiO intensity weighted velocity map as in Fig. 2. The seven ellipses (labelled a)–g)) shown in this middle panel correspond to the regions over which the spectra in the correspondingly labelled panels were averaged. The vertical blue line in each spectral panel corresponds to the V_lsr of the source (−3.4 km s^-1). The blue and green curves in these panels correspond to the narrow, low velocity (blue) and broad, high velocity (green) components of the outflow, both red and blue shifted from the rest velocity. The red curves show the sum of the broad and narrow components.