The lines were taken from
(1) W. Klebsch, M. Bester, K. M. T. Yamada, G. Winnewisser, W. Joentgen, H.-J. Altenbach, and E. Vogel, 1985, Astron. Astrophys. 152, L12.
The work included data from
(2) R. D. Brown, F. W. Eastwood, P. S. Elmes, and P. D. Godfrey, 1983, J. Am. Chem. Soc. 105, 6496;
and from
(3) T. B. Tang, H. Inokuchi, S. Saito, C. Yamada, and E. Hirota, 1985, Chem. Phys. Lett. 116, 83.
With respect to the Sep. 1997 entry, additional submillimeter lines have been considered. These data has been published by
(4) 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 reported in (2).