Panel a: Colour scale showing the integrated intensity map of the v_t = 1 CH₃ OH line at 334.4 GHz. The green triangles indicate the positions where the spectrum has been extracted for the rotational diagram analysis on the CH₃OH spots, and are labelled as components A and B. The black cross marks the position of the dust continuum peak. The beam is shown inthe lower left corner. Panel b: the colour scale shows the continuum emission from Fig. 2b, contours and markers are the same as in panel a. Panel c: Integrated spectrum of the torsionally excited CH₃ OH transition at 334.4 GHz over the area shown in panel a. The green lines show the two-component Gaussian fit to the spectrum. The blue dashed line shows the v_lsr of the source. Panel d: pv-diagram along the Δα axis and averaged over the extent of the cube we show here corresponding to ~2.5′′. The dotted lines mark the position of the dust peak and the v_lsr of the source.