The experimental data were taken from
(1) C. Cabezas, C. Barrientos, A. Largo, J.-C. Guillemin, J. Cernicharo, I. Peña, and J. L. Alonso, 2014, J. Chem. Phys. 141, Art. No. 104305.
Hyperfine structure splitting was resolved in the laboratory, but is deemed to be unimportant for astronomical observations. Predictions should be viewed with some caution above about 100 GHz.
The dipole moment was taken from an ab initio calculation in (1).