Very accurate microwave data along with some millimeter data were reported by
(1) S. Thorwirth, P. Theulé, C. A. Gottlieb, M. C. McCarthy, and P. Thaddeus, 2021, Astrophys. J. 662, 1309.
The calculations were truncated at J = 130. They should be sufficiently accurate for observations in cold sources, maybe even in lukewarm sources. Transition frequencies with uncertainties exceeding 0.1 MHz should be viewed with some caution.
The dipole moment is from a quantum chemical calculation in (1).