The experimental data was taken from
(1) M. Araki, H. Ozeki, and S. Saito, 1998, Astrophys. J. 496, L53.
The sextic centrifugal distortion constant H could not be determined from the present data set. Therefore, predicted uncertaintis should be viewed with some caution.
The dipole moment is from an ab initio calculation cited therein.
It should be noted that there is a very strong isotope effect on the dipole moment. The value calculated for iminodeuteromethylium, DCNH+, is below 0.01 D.