The data set has been extended greatly with respect to the first entry from Apr. 2000. Results from astronomical observations were used for the N = 1 – 0 and 2 – 1 transitions. These were taken mostly from
(1) C. Cabezas, M. Agúndez, N. Marcelino, B. Tercero, S. Cuadrado, J. Cernicharo, 2021, Astron. Astrophys. 654, Art. No. A45.
Two hyperfine lines were taken from
(2) K. Yoshida, N. Sakai, Y. Nishimura, T. Tokudome, Y. Watanabe, T. Sakai, S. Takano, and S. Yamamoto, 2019, Publ. Astron. Soc. Japan 71, Art. No. S18.
N = 3 – 2 data are from
(3) J. M. Vrtilek, C. A. Gottlieb, W. D. Langer, P. Thaddeus, and R. D. Wilson, 1985, Astrophys. J. 296, L35;
and N = 4 – 3 data are from
(4) M. Bogey, C. Demuynck, and J.-L. Destombes, 1985, Astron. Astrophys. 144, L15.
The calculations should now be sufficiently accurate for all observational purposes. Transition frequencies with calculated uncertainties exceeding 0.2 MHz should be viewed with some caution.
The dipole moment is assumed to be the same as for the main isotopolog, see e025501.cat.