Observations of carbon monoxide at 4.7 microns in IRC +10216, VY Canis Majoris, and NML Cygni.

Individual vibration-rotation lines of 12C'6O and 13C16O have been observed in !RC+ 10216, VY CMa, and NML Cyg, near 4.7 . The lines of CO seen in IRC+ 10216 are heavily saturated, yet quite narrow. Their widths, excitations, and radial velocity indicate physical association with the 2" diameter component of IRC+ 10216 known from lunar occultation measurements. The CO lines seen in VY CMa and NML Cyg correspond well to the more blueshifted of the emission features seen in OH, and must be associated with expanding circumstellar clouds. Subject headings: circumstellar shells - infrared sources - molecules - spectra, infrared