The lines were taken from
(1) R. D. Brown, P. D. Godfrey, P. S. Elmes, M. Rodler, and L. M. Tack, 1985, J. Am. Chem. Soc. 107, 4112;
and from
(2) L. Bizzocchi, C. Degli Esposti, and L. Dore, 2008, Astron. Astrophys. 492, 875.
NOTE: The partition function does not take into account vibrational contributions. According to ab initio calculations, the lowest vibrational state is at about 120 cm^–1. Approximate vibrational contributions to the partition function are available for some low-lying vibrational states.
The dipole moment was assumed to agree with that of the ground vibrational state, see e052501.cat.