The experimental data of the lowest energy conformer were taken from
(1) E. R. Alonso, B. A. McGuire, L. Kolesniková, P. B. Carroll, I. León, C. L. Brogan, T. R. Hunter, J.-C. Guillemin, and J. L. Alonso, 2019, Astrophys. J. 883, Art. No. 18.
The data were kindly communicated by E. R. Alonso. The present parameter set is slightly smaller than that in (1). Two conformers are considerably higher in energy. The predictions are probably sufficient for all needs of astronomers. Predictions with uncertainties larger than 0.3 MHz should be viewed with caution.
The ab initio dipole moment was given in (1).