Integrated intensity maps of HC₃N and CH₃CN in the 3 mm band observed with the IRAM 30m telescope. Observations covered the region shown in Fig. 2 but emission in these lines was only detected in the inner region shown here. The colour plot in each panel is the integrated emission of C¹⁸O(1–0) and contours correspond to molecular transitions as indicated above the panels. The intensities are integrated between velocities of −20 to 0 km s⁻¹. Contour levels in units of (K km s⁻¹) are indicated at the top of the panels. The HPBW is shown on the lower right.