Combined SMA + IRAM 30 m ¹³CO emission between –10 and 85 km s^-1. Contours are 10, 15, 20, 30 and 40× the map sensitivity 0.14 mJy beam^-1, for a spectral resolution of 5 km s^-1. The greyscale ranges from –0.14 to 8 mJy beam^-1. The beam size of 4.2′′× 2.9′′, PA = 0.7° is shown in the bottom left corner, which corresponds to the size of the SMA beam. The dashed white contour shows the combined 1.3 mm dust continuum emission at a level of 0.024 mJy beam^-1, the lowest black contour shown in Fig. 4. The coloured crosses correspond to the positions of the spectra shown in Fig. 12.