Rotational diagram of the CH₃OH (and isotopologue) transitions from Table 1. The colours correspond to the measurements on different positions: green shows the position marked A, red shows the position marked B, and blue corresponds to the central position marked by a cross in Fig. 4. The filled circles show the CH₃ OH lines, squares represent the ¹³CH₃OH lines, and triangles show the optically thick lines that are not used for the fit. The error bars show the linearly propagated errors from the Gaussian fit to the integrated intensities.