Please note that the identities of the exited states are not known. They have been numbered from low energies to higher energies. These two states are interacting strongely with each other.
The transition frequencies were taken from
(1) D. J. Tyree, T. W. Chapman, I. R. Medvedev, Z. Kisiel, 2022, J. Mol. Spectrosc. 390, Art. No. 111706.
A small number of lines with larger residuals was omitted. The parameter set differs slightly from that in (1). The calculations should be accurate enough for all observational purposes. Transition frequencies with calculated uncertainties larger than 0.2 MHz should be viewed with great caution.
The partition function considers the ground vibrational state only. Vibrational correction factors have been derived. Please do note the caveats ! Spin-statistical weights of the ratio 13 : 11 were omitted as they are close to 1 : 1. In v₃, K_a + K_c even and odd would carry the weights of 13 and 11, respectively, while it would be reversed for v₂.
The ground state dipole moment was determined in
(2) R. D. Brown, P. D. Godfrey, and J. Storey, 1975, J. Mol. Spectrosc. 58, 445.