The experimental transition frequencies were taken from
(1) R. L. Kuczkowski, F. J. Lovas, R. D. Suenram, R. P. Lattimer, K. W. Hillig II, and A. J. Ashe III, 1981, J. Mol. Struct. 72, 143.
Starting parameters were evaluated by scaling those of 3-butynenitrile. The reported uncertainties appear to be too conservative for the millimeter-wave data and even more so for he microwave data. They were adjusted.
With respect to the first entry of Feb. 2021, transition frequencies from an astronomical observation were added. These were published by
(2) R. Fuentetaja, M. Agúndez, C. Cabezas, B. Tercero, N. Marcelino, J. R. Pardo, P. de Vicente, and J. Cernicharo, 2024, Astron. Astrophys. 688, Art. No. L15.
The reported uncertainties from (2) were retained even though they appear to be slightly optimistic.
The calculations were truncated at J = 60 and 275 GHz. They should be sufficient for searches in dark clouds and probably luke-warm sources.
Transitions with calculated uncertainies exceeding 0.2 MHz should be viewed with caution. Spin-statistics were considered in the calculation.
The dipole moment was determined in (1).