The experimental lines were taken from
(1) M. C. McCarthy, E. S. Levine, A. J. Apponi, and P. Thaddeus, 2000, J. Mol. Spectrosc. 203, 75.
The conservative uncertainties were reduced by a factor of 2. The number of transition frequencies is too small to determine D reliably. Therefore, it was estimated from the main isotopolog. The calculated frequencies should be viewed with caution above 25 GHz.
The dipole moment was assumed to agree with that of the main isotopic species calculated by
(2) P. Botschwina and M. Horn, 1997, J. Mol. Spectrosc. 185, 191.