The synperiplanar conformer is by far the lowest one. The anticlinal conformer, also known as gauche, is so much higher in energy that no transitions have been observed; it is unlikely to be important for radio astronomy. The transition frequencies were reported by
(1) R. A. Motiyenko, L. Margulès, and J.-C. Guillemin, 2013, Astron. Astrophys., 559, Art. No. A44.
As the reported uncertainties were slightly conservative, we employed uncertainties close to those implicitely assumed. The predictions should be well sufficient for radio astronomical observations. Transitions with predicted uncertainties larger than 300 kHz should be viewed with some caution.
The ¹⁴N hyperfine splitting should be unimportant for radio astronomical observations.
The ab initio dipole moment components were reported in (1).