The observed transitions were taken from
(1) L. Margulès, A. Belloche, H. S. P. Müller, R. A. Motiyenko, J.-C. Guillemin, R. T. Garrod, and K. M. Menten, 2016, Astron. Astrophys. 590, Art. No. A93.
The predictions are deemed to be reliable throughout for astronomical observations. Predictions with uncertainties exceeding 0.5 MHz should be viewed with caution.
The partition function values below refer to the ground vibrational state only. Vibrational correction factors have been derived for the main isotopolog in the harmonic approximation. Errors caused by isotopic substitution are small.
The dipole moment was assumed to agree with that of the main isotopic species:
(2) A. Krasnicki, Z. Kisiel, 2011, J. Mol. Spectrosc. 270, 83.
Some small deviations are expected to occur, but these are essentially negligible.