Isocyanic acid in the Taurus Molecular Cloud 1

The detection of the 1(01)-0(00) line of isocyanic acid (HNCO) in the Taurus Molecular Cloud 1 (TMC-1) is reported. This is the first time that this species has been identified in a molecular cloud other than the cloud associated with Sgr B2. The hyperfine structure of the transition is clearly resolved in TMC-1, but the intensities of the hyperfine components are not in the LTE ratio 5:3:1; rather, the ratios are found to be approximately 5:2:1. Since the abundance of HNCO is similar to that expected from chemical models of TMC-1, it is anticipated that this species will also be detectable elsewhere in the Galaxy.