The first entry of June 2001 was based mostly on
(1) G. Klapper, F. Lewen, R. Gendriesch, S. P. Belov, and G. Winnewisser, 2001, Z. Naturforsch. A, 56, 329.
We retain J" = 2 – 7 and 15 – 17 (all but J" = 1) in the present evaluation.
The J" = 0 and 1 transitions frequencies were taken from
(2) G. Cazzoli, C. Puzzarini, and A. V. Lapinov, 2003, Astrophys. J., 592, L95.
The J" = 22 and 23 frequencies were taken from
(3) J. C. Pearson, B. J. Drouin, A. Maestrini, I. Mehdi, J. Ward, R. H. Lin, S. Yu, J. J. Gill, B. Thomas, C. Lee, G. Chattopadhyay, E. Schlecht, F. W. Maiwald, P. F. Goldsmith, and P. Siegel, 2011, Rev. Sci. Instrum., 82, Art. No. 093105.
The transition frequencies should be quite reliable up to about 3.4 THz. Great caution is advised above 4.4 THz. Please note that the partition function still only refers to the ground vibrational state.
The dipole moment and dipole centrifugal corrections were taken from
(2) D. Goorvitch, 1994, Astrophys. J. Suppl. 95, 535.