Extensive experimental laboratory frequencies up to 40 GHz, hyperfine parameters, and the dipole moment were reported in
(1) M. Hahn, H.-K. Bodenseh, and M. Ferner, 2004, J. Mol. Spectrosc. 223, 138.
With respect to the first entry from June 2006, additional data, largely in the millimeter region, were included from
(2) L. Margulès, B. A. McGuire, R. A. Motiyenko, C. Brogan, T. Hunter, A. Remijan, and J.-C. Guillemin, 2020, Astron. Astrophys. 637, Art. No. A81.
The calculations should be sufficient for all observational purposes. Caution is advised for transitions having calculated uncertainties in excess of 0.2 MHz. The ¹⁴N hyperfine splitting may be resolvable at lower frequencies or at lower quantum numbers. Therefore, a separate calculation with hyperfine structure is available up to 188 GHz and with J up to 5. The spin-multiplicity of the ¹⁴N nucleus was considered in the calculation of the partition function.