Transition frequencies with microwave accuracy were determined by
(1) D. Dangoisse, E. Willemot, and J. Bellet, 1978, J. Mol. Spectrosc. 71, 414;
and by
(2) O. Zakharenko, R. A. Motiyenko, L. Margulès, and T. R. Huet, 2015, J. Mol. Spectrosc. 317, 41.
Some higher order parameters were estimated from the D₂CO parameters.
The uncertainties of (2) appeared to be quite conservative. Therefore, we decreased these uncertainties by a factor of 1.5. The data from (1) have not been merged.
The predictions of very high lying rotational states have been improved with respect to the first entry. The predictions should be adequate throughout not only for astronomical observations but also for laboratory spectroscopy.
At low temperatures, it may be necessary to discern between ortho-D₂CO and para-D₂CO. The ortho states are described by K_a even, the para states by K_a odd. The nuclear spin-weight ratio is 2 : 1 for ortho-D₂¹³CO : para-D₂¹³CO. The J_KaKc = 1₁₁ is the lowest para state. It is 5.5608 cm^–1 above ground.
The dipole moment was assumed to agree with that of D₂CO, see e032502.cat.