The microwave data of the first entry of Dec. 2021 were contributed by
(1) L. H. Scharpen and V. W. Laurie, 1965, J. Chem. Phys. 43, 2765;
while the millimeter-wave data were taken from
(2) L. Bonah, B. Helmstaedter, J.-C. Guillemin, S. Schlemmer, and S. Thorwirth, 2025, J. Mol. Spectrosc. 408, Art. No. 111967.
The data fit to roughly 15 kHz using an S-reduced Hamiltonian.
The calculations were truncated at J = 50 and at 500 GHz. They should be sufficient for all observational purposes. Transition frequencies with calculated uncertainties exceeding 0.1 MHz should be viewed with caution.
Non-trivial spin-statistics do not matter for this isotopolog.
The total dipole moment was assumed to agree with that of the main isotopolog; the relative magnitudes were taken from an MP2 quantum-chemical calculation by
(3) H. S. P. Müller, 2021, unpublished.
The a-component should be taken with some caution even though it looks like non of these transitions were above the intensity cut-offs.