The molecule displays internal rotation of the methyl group. The present analysis is based on the data from
(1) K. G. Lengsfeld, P. Buschmann, F. Dohrmann, J.-U. Grabow, 2021, J. Mol. Spectrosc. 378, Art. No. 111441.
The parameter set differs from the published one. The calculation was truncated at J = 20 ans 211 GHz because of the limitated quantum number range. The calculation should be sufficient for observations in colder sources. Transitions with calculated uncertainties exceeding 0.1 MHz should be viewed with caution.
Please note that state number 0 and 1 refer to the A and E symmetry components, respectively. This differs slightly from the standard erham notation.
The partition function refers to the complete ground vibrational state which was evaluated with g_I = 1.
The dipole moment components were determined by
(2) O. L. Stiefvater, J. J. Sheridan, 1963, Proc. Chem. Soc. 368.