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C. L. Gerardy, R. A. Fesen (Dartmouth College), P. H\"oflich, J. C. Wheeler (Univ. of Texas)
We present near-infrared \textit{J}, \textit{H}, and \textit{K} spectra of the Type~IIn supernova 1998S in NGC~3877 taken ~100 days after maximum brightness with the 2.4m Hilter telescope at MDM. To our knowledge, this is the first near-infrared spectrum of a Type~IIn event. The data show broad emission from hydrogen recombination lines, as well as emission from the first and second overtone bands of CO in the \textit{H} and \textit{K} spectra. Preliminary analysis suggests a CO overabundance of ~2 and a temperature in the CO forming region of 4000 to 4500 K. This is the third detection of CO emission in a Type~II supernova, and may indicate that molecule formation is common in Type~II events. The detected presence of CO in supernovae is important as molecular emission can be a strong coolant and is a first step toward dust formation.