DPS 34th Meeting, October 2002
Session 34. Titan
Poster, Chair(s): , Thursday, October 10, 2002, 4:00-6:30pm, Exhibit Hall

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[34.04] Characterizing the Methane and Haze Distribution in Titan's Lower Atmosphere

C.M. Anderson, N.J. Chanover (New Mexico State University), C.P. Mckay (NASA/ARC), P. Rannou (Universite de Paris), D.A. Glenar (NASA/GSFC), J. Hillman (University of Maryland)

Titan was observed in November 1999 and 2000 with the Mount Wilson 100'' Hooker telescope equipped with a natural guide star adaptive optics system. The images were taken with the NASA/GSFC-built Acousto-Optic Imaging Spectrometer (AImS), which utilizes a tunable filter element coupled to a CCD camera system. Narrow-band images of Titan were obtained at 890,920, 930, 940, 950, and 960 nm. The wavelengths between 890 and surrounding the 940 nm window provide an enhanced vertical resolution because the wavelengths are sensitive to different vertical locations in Titan's atmosphere. We use variations of absolute reflectivity across Titan's disk to probe the haze properties in the 1 micron region. This region represents a transition between optically thick haze at shorter wavelengths and optically thin haze at longer wavelengths. Our understanding of Titan's haze in the 1 micron region through ground-based observations has been limited by the presence of a terrestrial water band in this region. We were able to alleviate this observational constraint by exploiting the high spectral resolution of the AOTF camera system, which allowed us to isolate narrow regions of high atmospheric transmission. We fit the Minnaert function to our observations and radiative transfer modeling output to determine limb darkening coefficients. We characterize the vertical distribution in the methane and haze through direct comparison between the shape of the modeled and observed limb darkening profiles.

This work has been supported by the National Science Foundation grant AST-0074923 and the Harriet G. Jenkins Predoctoral Fellowship Program.

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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.