A survey of organic volatile species in comet C/1999 H1 (Lee) using NIRSPEC at the Keck Observatory

The organic volatile composition of the long-period comet C/1999 H1 (Lee) w as investigated using the first of a new generation of cross-dispersed cryo genic infrared spectrometers (NIRSPEC, at the Keck Observatory atop Mauna K ea, HI). On 1999 August 19-21 the organics spectral region (2.9-3.7 mum) wa s completely sampled at both moderate and high dispersion, along with the C O fundamental region (near 4.67 mum), revealing emission from water, carbon monoxide, methanol, methane, ethane, acetylene, and hydrogen cyanide. Many new multiplets from OH in the 1-0 band were seen in prompt emission, and n umerous new spectral lines were detected. Several spectral extracts are sho wn, and global production rates are presented for seven parent volatiles. C arbon monoxide is strongly depleted in comet Lee relative to comets Hyakuta ke and Hale-Bopp, demonstrating that chemical diversity occurred in the gia nt-planets' nebular region.