(a) Contour map of the 7 mm continuum emission (enlargement of the map in Fig. 1) overlaid on the H40α velocity map (colour image) of Fig. 4. The dashed line marks the approximate axis of the cometary shaped UC HII region as well as the approximate direction of the velocity gradient across it. (b) Same as panel a, for the line FWHM. The synthesised beams are shown in the bottom left (for the 7 mm map) and right (for the velocity map) corners.