The cyanide ion has been detected with the IRAM 30 m
telescope in the circumstellar shell of the carbon rich star
CW Leo (IRC +10216) in 3 rotational transitions from
J = 1 0 to 3 2
which occur between 110 and 340 GHz:
M. Agúndez, J. Cernicharo, M. Guélin, C. Kahane, E. Roueff, J. Klos, F. J. Aoiz, F. Lique, N. Marceliño, J. R. Goicoechea, M. González García, C. A. Gottlieb, M. C. McCarthy, and P. Thaddeus,
Astronomical Identification of CN, the Smallest Observed Molecular Anion
Astron. Astrophys. 517, Art. No. L2 (2010).
It should be mentioned that the 1 0 transition is heavily blended with a line of C6H, however a weak shoulder seems to be due to the anion. The 2 1 transitions is partially blended, partially it appears to be clear. The 3 2 transition seems to be unblended. The number of transitions is somewhat low, nevertheless, the detection appears to be safe, in particular when one takes into consideration the line shapes, abundance, and rotational temperature.