Transition frequencies were taken from
(1) P. M. Sheridan, M. A. Brewster, L. M. Ziurys, 2002, Astrophys. J. 576, 1108.
The partition function does not take into account vibrational corrections. The predictions should be sufficiently accurate for observational purposes. The dipole moment was determined by
(2) T. C. Steimle, D. F. Nachman, J. E. Shirley, C. W. Bauschlicher Jr. and S. R. Langhoff, 1989, J. Chem. Phys. 91, 2049.