The discovery was confirmed with a coudé spectrograph, which was made famous and credible due to this detection.

[2] A spectral line of •CN was detected in 1938 in the interstellar medium in the ultraviolet, and was identified in 1940 by Andrew McKellar.

The coudé spectrograph and a 100-inch (2.5 m) telescope were used to observe •CN's interstellar lines and ultraviolet spectra.

[7] In 1991, the •CN vibration-rotational bands were observed in a king furnace at the National Solar Observatory using a McMath Fourier-Transform spectrometer.

[6] In 1995, the rotational absorption spectrum of ·CN in the ground state was observed in the 1 THz region, and most of the lines were measured in the range of 560 to 1020 GHz.