Experimental results were published by
(1) E. Kagi and K. Kawaguchi, 1997, Astrophys. J. 491, L129.
The ²³Na hyperfine split a-type transition frequencies were also included in the fit. They were reported by
(2) M. P. Bucchino, P. M. Sheridan, J. P. Young, M. K. L. Binns, D. W. Ewing, and L. M. Ziurys, 2013, J. Chem. Phys. 139, Art. No. 214307.
The experimental transition frequencies from (1) were kindly provided by K. Kawaguchi.
²³Na HFS splitting may be resolvable at low values of J and higher values of K_a, but these transitions are deemed to be too weak even if the molecule will have been observed in space. The entry may be sufficiently accurate for all observational purposes. Transitions with predicted uncertainties exceeding 0.2 MHz should be viewed with some caution.
The dipole moment was taken from an ab initio calculation mentioned in (1). Even though the molecule posseses a moderately large b-dipole moment component, no such transitions were calculated because their frequencies are too uncertain.