The lines were taken from
(1) S. Brünken, Z. Yu, C. A. Gottlieb, M. C. McCarthy, and P. Thaddeus, 2009, Astrophys. J. 706, 1588.
Predictions with uncertainties exceeding 0.5 MHz should be viewed with caution. Moreover, predictions of transitions with K_a ≥ 7 should be viewed with caution also.
¹⁴N hyperfine splitting may be resolved for low values of J. Therefore, a separate hyperfine calculation is provided for J' ≤ 10 and K_a ≤ 1. NOTE: The partition function does not take into account the spin multiplicity g_I = 3 of the ¹⁴N nucleus !
The ab initio dipole moment was mentioned taken from
(2) D. E. Woon and E. Herbst, 2009, Astrophys. J. Suppl. Ser. 185, 273.
The molecule has also a moderately large b-dipole moment component. However, predictions would be completely unreliable at present and have thus been omitted.