The new entry is completely different from the first one from Dec. 1999. Essentially all measured transition frequencies were taken from
(1) L. Margulès, R. A. Motiyenko, and J. Demaison, 2020, J. Quant. Spectrosc. Radiat. Transfer 253, Art. No. 107153.
A single highly accurate MW frequency was taken from
(2) H. S. P. Müller, J. Farhoomand, E. A. Cohen, B. Brupbacher-Gatehouse, M. Schäfer, A. Bauder, and G. Winnewisser, 2000, J. Mol. Spectrosc. 201, 1.
All other earlier data were omitted because of lower accuracies. The uncertainties in (1) are nearly 2.5 σ values; they were adjusted to result in an rms error of slightly less than 1.0. Some higher order distortion parameters were fixed to values derived from the ³²SO₂ isotopolog.
The calculation should be sufficient for all observational purposes. Frequencies with calculated uncertainties exceeding 0.2 MHz should be viewed with caution.
The dipole moment is assumed to be the same as for the ³²S isotopolog; the rotation of the inertial axis system has been taken into account. The intensity thresholds were lowered such that low-J a-type transitions are calculated despite their very low intensities.