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N. Dello Russo (CUA/NASA-GSFC), M. J. Mumma (NASA-GSFC), M. A. DiSanti (CUA/NASA-GSFC), K. Magee-Sauer (Rowan University), R. Novak (Iona College), T. W. Rettig (University of Notre Dame)
High-resolution (R = 15000-23000) spectra of comets Lee and Linear S4 were obtained atop Mauna Kea, HI with CSHELL at the IRTF and NIRSPEC at the Keck Observatory. Comet Lee was observed UT 1999 Aug 16.6-21.6, and Linear S4 was observed UT 2000 Jul 3.7-5.8 and Jul 21.6. A spectral comparison of these two Oort cloud comets between 3.26-3.53 microns shows a striking depletion of the organic volatiles methanol, methane, and ethane in Linear S4 relative to Lee. This is in contrast to the remarkably similar relative abundances of these species measured in Hyakutake, Hale-Bopp and Lee. Production rates and relative abundances of these volatiles will be reported for Linear S4 and Lee on the dates observed.
This work is supported by the NASA Planetary Atmospheres Program (Grant NAG5-7753).