HCN (not HNC) was first detected in June 1970 by L. E. Snyder and D. Buhl using the 36-foot radio telescope of the National Radio Astronomy Observatory. The main molecular isotope, H12C14N, was observed via its "J" = 1→0 transition at 88.6 GHz in six different sources: W3 (OH), Orion A, Sgr A(NH3A), W49, W51, DR 21(OH). A secondary molecular isotope, H13C14N, was observed via its "J" = 1→0 transition at 86.3 GHz in only two of these sources: Orion A and Sgr A(NH3A). HCN was then later detected extragalactically in 1988 using the IRAM 30-m telescope at the Pico de Veleta in Spain. It was observed via its "J" = 1→0 transition at 90.7 GHz toward IC 342.