The experimental data were summarized by
(1) H. S. P. Müller and F. Lewen, 2017, J. Mol. Spectrosc. 331, 28.
Besides new submillimeter data up to 1.5 THz from that study, transition frequencies were taken from
(2) W. H. Flygare and J. T. Lowe, 1965, J. Chem. Phys. 43, 3645;
and from
(3) R. Cornet, B. M. Landsberg, and G. Winnewisser, 1980, J. Mol. Spectrosc. 82, 253.
The predictions should be accurate enough for all astronomical observations. Predictions with calculated uncertainties exceeding 0.2 MHz should be viewed with caution.
The ¹H hyperfine splitting has not been resolved in the laboratory and is unlikely to matter in astronomical observations. ¹⁷O hyperfine splitting is important at long wavelength, but probably negligible in the submillimeter. A separate hyperfine calculation is provided up to 600 GHz. The partition function takes into account the hyperfine splitting.
At low temperatures, it may be necessary to discern between ortho-H₂C¹⁷O and para-H₂C¹⁷O. The ortho states are described by K_a odd, the para states by K_a even. The nuclear spin-weights are 3 and 1 for ortho-H₂C¹⁷O and para-H₂C¹⁷O, respectively. The J_KaKc = 1₁₁ is the lowest ortho state. It is 10.5126 cm^–1 above ground.
The dipole moment was assumed to agree with that of the main isotopolog, see e030501.cat.