The majority of the data were taken from
(1) L. Margulès, B. Tercero, J.-C. Guillemin, R. A. Motiyenko, and J. Cernicharo, 2018, Astron. Astrophys., 610, Art. No. A44.
Additional data were contributed by
(2) R. J. Anderson and W. D. Gwinn, 1968, J. Chem. Phys., 49, 3988;
by
(3) E. Fliege and H. Dreizler, 1985, Z. Naturforsch. A, 40, 43;
and in particular by
(4) M. Krüger and H. Dreizler, 1992, Z. Naturforsch. A, 47, 1067.
The parameter set is similar to the S-reduction set in (1). The predictions are sufficiently accurate for all astronomical observations. They should be viewed with caution once the predicted uncertainties exceed 0.2 MHz. Internal rotation as well as ¹⁴N hyperfine structure splitting are probably unimportant for all astronomical observations.
The dipole moment components were determined in (2).