Central panel: velocity integrated intensity of the 5₋₁ → 4₀ − E methanol line at 84.5 GHz obtained by integrating the channels inside the colored areas shown in the side panels. Regions where we detect Class I maser emission in the J₋₁ → (J − 1)₀ − E series (see Sect. 4.1.2) are labeled in red and with slightly larger numbers. Side panels: methanol spectra of the different regions as labeled in the top right corner of each panel (a v_sys of 258.8 km s⁻¹ was subtracted). Vertical lines indicate the peak velocity of the ¹³CO J = 1 − 0 line (110.2 GHz) extracted in each region, as a reference for the systemic velocity at that position. Coordinate system, beam size and other parameters are the same as in Fig. 1.