Stacked line of C₆H₅CN obtained from the average in each position of 52 individual lines (see Appendix B). Only the spectra around the region of maximum emission (see Fig. 2) are shown. The offset positions in arcseconds are indicated in each panel. The abscissa in each panel corresponds to the local standard of rest velocity of the stacked data (in km s⁻¹). The intensity scale corresponds to the antenna temperature corrected for atmospheric transmission and antenna losses.