36th DPS Meeting, 8-12 November 2004
Session 33 Comets: Comae
Poster II, Thursday, November 11, 2004, 4:15-7:00pm, Exhibition Hall 1A

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[33.08] Infrared Spectroscopy of C/1999 T1 (McNaught-Hartley)

R.J. Vervack, Jr., H.A. Weaver (JHU/APL), G. Chin (NASA/GSFC), N.A. Levenson (UKy), J.K. Davies (ROE), S.J. Kim (Kyunghee U), D. Bockelée-Morvan, N. Biver, J. Crovisier (Obs.Meudon/Paris), T.Y. Brooke (Caltech)

We report on infrared spectroscopic observations of the long-period comet C/1999~T1 (McNaught-Hartley) made from the Keck Observatory during 2001 February~5-6 UT. At that time, the comet's heliocentric distance was 1.44--1.45~AU, the geocentric distance was 1.29~AU, the geocentric radial velocity was \sim1.5--2.4 km s^{-1}, and the water production rate was \sim5 \times 10^{28} s^{-1}. We used the NIRSPEC instrument, which is a cross-dispersed grating spectrometer, to cover the entire wavelength range between 2.88~\mum and 3.72~\mum with a spectral resolving power of ~20,000. We also obtained spectra of selected regions in the M-band (near 5~\mum) and K-band (between 2.0~\mum and 2.5~\mum). Numerous cometary lines were detected, including emissions from C\rm 2H\rm 6, CH\rm 3OH, H\rm 2O, OH (both prompt and fluorescent emissions), and possibly HCN, C\rm 2H\rm 2, and CH\rm 4. As the NIRSPEC spectral images exhibit both spatial and spectral distortions, we developed an IDL-based analysis tool that performs a true, 2-dimensional rectification of the data. Using this tool, which is general enough to be applied to data obtained with other instruments, we can extract spectra of optimal signal-to-noise ratio and perform accurate analyses of the spatial brightness distributions of the various species. We present results using this tool for the 33 separate spectral orders covered during our NIRSPEC observations of C/McNaught-Hartley.

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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.