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N. J. Chanover, C. A. Anderson (New Mexico State Univ.), C. McKay (NASA/ARC), P. Rannou (Univ. de Paris 6), D. A. Glenar (NASA/GSFC), J. J. Hillman (U. Maryland)
Narrow-band images of Titan were obtained in November 1999 with the NASA/GSFC-built Acousto-optic Imaging Spectrometer (AImS) camera. This instrument utilizes a tunable filter element that was used within the 500 -- 1050 nm range, coupled to a CCD camera system. The images were taken with the Mount Wilson 100'' Hooker telescope, which is equipped with a natural guide star adaptive optics system. We analyzed images of Titan taken at 890 nm, at the center of a methane absorption band, and at 940 nm, in a window in Titan's atmosphere where the methane opacity is relatively low. We used the variation of absolute reflectivity across Titan's disk to further our understanding of the nature of the haze in Titan's lower atmosphere. We fit a limb darkening coefficient to latitudinal scans across Titan's disk at the sub-Earth point in the southern hemisphere and near the equator. Using two radiative transfer codes that treat Titan's haze particles as spherical and fractal particles, respectively, we modeled Titan's atmosphere and explored the parameter space that best matched our observed reflectivity variations across Titan's disk. The results of this modeling and their implications for the structure of Titan's lower atmosphere will be discussed. This work has been supported by the National Science Foundation through grant AST-0074923.
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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.