Maps of emission from the 3–2 transitions of CO, ¹³CO, C¹⁷O, transitions of N-bearing molecules, HCO⁺ and H¹³CO⁺ 4–3. White contours represent integrated line emission and are at 90%, 80%, ..., 10% of the maximum intensity, listed in Table 2. The contour at 50% is thicker. An extra contour is added for HNC 4–3 at 5% of the maximum intensity. The beam size at the relevant frequency is indicated in the top right corner of each panel. To avoid noise in the figures, contours below 0.7 K   km   s^-1 are not shown. SCUBA 850 μm continuum emission is shown in color scale and thin black contours; the color scale is stretched from 10 to 5600 mJy beam^-1.