Rotationally resolved infrared absorption spectra for the 1(0)(1) band of jet cooled cobalt tricarbonyl nitrosyl have been observed and analyzed. Several longitudinal modes of a Pb-salt diode laser were utilized to measure 105 rovibrational transitions for this particular vibrational band centered near 2112 cm-1. Spectra were optimized using both argon and helium carrier gases and these experiments eventually led to rovibrational transitions being assigned to four different K subbands, specifically the K=0, 3, 6, and 9 subbands. An iterative least-squares analysis of the spectroscopic data yielded the following molecular parameters nu(0)=2111.7457(9) cm(-1), B-0=0.034747(12) cm(-1), B-1=0.034695(15) cm(-1), C-1=0.03380(9) cm(-1), and D-1K=6.3(9)x10(-6) cm(-1) (where 3sigma uncertainties are listed in parenthesis). (C) 2004 American Institute of Physics.