Excitation temperature (T_ex, left) and optical depth (τ, right) maps derived from the HFS fitting after being convolved with a Gaussian FWHM beam of 32′′ (Gaussian kernel ~13.59′′). The thick white contour in each panel traces the 3σ level of the respective ¹²C isotopologue line integrated intensity shown in Fig. 2. The red circles mark the locations whose spectra are shown in Fig. A.2. The beams and polygons are the same as in Fig. 2.