Results of the rotational diagrams for CH₃CN ν = 0, CH₃CN ν₈ = 1, CH₃OCHO, HNCO, CH₂DOH and aGg’-(CH₂OH)₂. The high rotation temperature fitted to the CH₃CN ν = 0 rotational diagram is the consequence of the lines being optically thick and is not considered in our modeling (see Sect. 4.1). In the rotational diagram of the CH₃CN ν₈ = 1 vibrational state we use different symbols for: blended lines (empty circles), isolated or partially blended lines (filled circles), and the points with E_rot> 400 K (triangles). The three straight lines correspond to the least squares fittings with all the points (black), only unblended lines (red), and unblended lines with E_rot< 400 K (blue). For CH₃OCHO, the points corresponding to the ν = 0 lines are indicated with filled circles and ν_t = 1 with empty circles. The parameters of the transitions used in the rotation diagrams are listed in Tables A.3–A.8. Red points have not been used in the least squares fitting because they correspond to heavily blended lines.