The lines were taken from
(1) A. L. Cooksy, J. K. G. Watson, C. A. Gottlieb, and P. Thaddeus, 1992, J. Mol. Spectrosc. 153, 610; and from
(2) W. Chen, S. E. Novick, M. C. McCarthy, M. J. Travers, C. A. Gottlieb, A. L. Cooksy, and P. Thaddeus, 1996, Astrophys. J. 462, 562.
Accidentally large hyperfine splitting at higher values of N are possibly not fully accounted for by the present data set. Accordingly, these predictions should be viewed with a grain of salt.
The dipole moment was taken from an ab initio calculation by
(3) A. L. Cooksy, F.-M. Tao, W. Klemperer, and P. Thaddeus, 1995, J. Phys. Chem. 99, 11095.
Transitions with b-type selection rules are allowed, but have not been measured yet. Hence, they cannot be predicted reliably.