The experimental measurements were taken from
(1) S. Brünken, C. A. Gottlieb, H. Gupta, M. C. McCarthy, and P. Thaddeus, 2007, Astron. Astrophys., 464, L33.
With respect to the Mar. 2007 entry, several submillimeter transitions up to about 830 GHz were used in the fit. They were published by
(2) T. Amano, 2008, J. Chem. Phys. 129, Art. No. 244305.
The predictions should be reliable up to about 2 THz.
The ab initio dipole moment was taken from
(3) M. Mladenovic, P. Botschwina, P. Sebald, and S. Carter, 1998, Theor. Chem. Acc. 100, 134.