With respect to the first entry from Feb. 2023, lines from astronomical observations were employed. These were reported by
(1) J. R. Pardo, C. Cabezas, M. Agúndez, B. Tercero, N. Marcelino, P. de Vicente, M. Guélin, and J. Cernicharo, 2023, Astron. Astrophys., 677, A55.
While the rotational parameter B was floated, the distortion parameter was kept fixed to the value from
(2) A. Remijan, H. N. Scolati, A. M. Burkhardt, P. B. Changala, S. B. Charnley, I. R. Cooke, M. A. Cordiner, H. Gupta, E. Herbst, K. L. K. Lee, R. A. Loomis, C. N. Shingledecker, M. A. Siebert, C. Xue, M. C. McCarthy, and B. A. McGuire, 2023, Astrophys. J. Lett., 944, L57.
Please note that the distortion parameter is a guess value, but it is well compatible with the observational data. The calculations may be reasonable throughout.
The dipole moment was taken from a quantum chemical calculation in
(3) S. J. Blanksby, A. M. McAnoy, S. Dua, and J. H. Bowie, 2001, Mon. Not. R. Astron. Soc. 328, 89.