Transition frequencies were reported by
(1) Y. Motoki, F. Isobe, H. Ozeki, and K. Kobayashi, 2014, Astron. Astrophys. 566, Art. No. A28.
The authors retained in their fit also few data from
(2) R. Pearson, Jr. and F. J. Lovas, 1977, J. Chem. Phys. 66, 4149.
Data with uncertainties of 100 kHz or more were not merged. The predictions should be accurate enough for all radioastronomical observations. Specifically, predictions with uncertainties larger than 0.3 MHz should be viewed with some caution.
¹⁴N hyperfine splitting may matter in astronomical observations. Therefore, a separate hyperfine calculation is provided for J' ≤ 20 and K_a' ≤ 5 up to 1 THz. NOTE: The partition function does take into account the spin multiplicity of the ¹⁴N nucleus !
The dipole moment components were assumed to agree with those of the main species reported by
(3) M. Allegrini, J. W. C. Johns, and A. R. W. McKellar, 1979, J. Chem. Phys. 70, 2829.