Highly excited lines of CHD₂OH (out of the 105 used for synthetic spectral fitting) that drive the best-fitting excitation temperature to lower values (Sect. 3.1). The observed spectrum is in dark blue, the reference spectrum is in turquoise, and the best-fitting synthetic spectrum (T_ex =90 K) is in pink. The best- fitting models for fixed T_ex = 150 and 300 K are overlaid in lilac and green, respectively. The rest frequency, E_up (K), A_ij (s⁻¹), and optical depth (for the best-fitting parameters) are shown in the right corner of each panel. The rest frequency is indicated with a vertical dashed line, and the filled yellow region corresponds to the uncertainty on that line frequency. The lines at 342.477 and 333.313 GHz are in fact overlapping double transitions.