Rotational diagrams for the torsionally excited states, ν₁₁ = 1 (left) and ν₁₅ = 1 (right), of dimethyl ether. The filled squares (■) indicate transitions detected with the SHeFI instrument, the open squares (Λ) detections with the CHAMP⁺ instrument. The solid line represents the fit to the torsionally excited states and the dotted line indicates the fit to the ground state transitions with E_u > 200 K. The least-square fit to the torsionally excited state, ν₁₁ = 1 gives a resulting N_T of 7.5 × 10¹⁷ cm^-2 and a T_rot of 95 K. For the torsionally excited state, ν₁₅ = 1, these values are 6.3 × 10¹⁷ cm^-2 and 107 K, respectively.