Program: GN-2011A-Q-36

We seek to obtain spectra of Titan and Saturn at the highest resolving power (R ~ 18,000) available with GNIRS in the methane transparency windows at 1.55 and 2 microns. In the past spectra of these objects at this resolution were impossible to properly analyse because the available spectral line lists for the important species (CH4 in Titan, and CH4 & NH3 in Saturn) were completely inadequate at wavelengths shorter than ~ 2.1 microns. This situation has changed recently with the publication of several new sets of high-quality, low-temperature measurements of methane spectral lines. These have enabled us to construct a new methane line-list, that provides a good model for the Titan spectrum in the 1.3 - 1.8 micron region. A new ammonia line list is also available due to Yurchenko et al. (2009). We will use these new line lists in conjunction with our planetary atmosphere radiative transfer model VSTAR to model the observed spectra. The project will allow us to verify the completeness and accuracy of the new line lists, to enable the search for absorptions due to trace atmospheric constituents, to study the isotope ratios in the atmosphere, and to better define the atmospheric cloud structures.