DPS 2001 meeting, November 2001
Session 38. Titan Posters
Displayed, 9:00am Tuesday - 3:00pm Saturday, Highlighted, Friday, November 30, 2001, 9:00-10:30am, French Market Exhibit Hall

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[38.07] The Nature of the Haze in Titan's Lower Atmosphere

C.M. Anderson, N.J. Chanover, D.W. Lofton (New Mexico State Univ.), D.A. Glenar (NASA/GSFC), C. McKay (NASA/ARC), P. Rannou (U. de Paris)

Narrow-band images of Titan were obtained in November 1999 and 2000 with the NASA/GSFC-built Acousto-optic Imaging Spectrometer (AImS) camera. This instrument utilizes a tunable filter element that we 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 observed Titan at 830 and 890 nm, along with a series of wavelengths across the 940 nm "window" in Titan's atmosphere where the methane opacity is relatively low. Spectrophotometric standard star data were taken concurrently with our Titan observations. In analyzing the data we performed standard image reduction techniques to all Titan and star images. The narrow band images of Titan were geometrically navigated in order to determine Titan's North Angle location and orientation. The Titan data were also photometrically calibrated; the standard star data were utilized to obtain the absolute reflectivity of Titan as a function of atmospheric slant path.

Using the variation of absolute reflectivity across Titan's disk, our goal is to further our understanding of the nature of the haze in Titan's lower atmosphere. The 1 micron region is important for probing the haze properties because this spectral region represents a transition between optically thick haze, at shorter wavelengths, and optically thin haze at longer wavelengths. Ground-based observations in this wavelength region are relatively scarce due to the presence of a terrestrial water band in this spectral region, therefore our understanding of Titan's haze at these wavelengths is largely through modeling efforts. The high spectral resolution of the AOTF camera system allows us to isolate narrow regions of high atmospheric transmission, thereby alleviating this observational constraint. Through radiative transfer modeling of Titan's atmosphere that we used to fit our observed reflectivity variations across Titan's disk, we present preliminary insights into the properties of the haze in Titan's lower atmosphere.

Support for this work is provided by the Mount Wilson institute and the National Science Foundation.

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