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D.B. Campbell (Cornell/NAIC), G.J. Black (NRAO), J-L. Margot, M. Nolan (NAIC), S.J. Ostro, M. Slade (JPL)
The 13 cm wavelength radar system on the 305 m Arecibo telescope was used in October and November, 1999 to observe Titan. Observations took place on nine nights spanning the whole range of Titan longitudes. A circularly polarized wave was transmitted and the backscatter cross section measured in both the expected or OC sense of receive circular polarization and in the cross polarized or SC sense. Initial reduction of the observations gave a mean OC cross section of 16% ± 3 of Titan's projected area and a circular polarization ratio (the ratio of the SC to OC cross sections) of 0.6 ± 0.2. The mean OC cross section is slightly higher than the 12.5% reported by Muhleman et al. (Ann. Rev. Earth Planet. Sci., 1995, Vol. 23) at 3.5 cm wavelength. The high polarization ratio is indicative of either a very rough surface at wavelength scales or, possibly, sub-surface multiple scattering. The 13 cm OC cross section varies between 6% and 24% as a function of longitude, a somewhat smaller range than that reported by Muhleman et al. at 3.5 cm.
The Arecibo Observatory is part of the National Astronomy and Ionosphere Center which is operated by Cornell University under a cooperative agreement the National Science Foundation. Additional support is provided by NASA. DBC, SJO and MS were partially supported by NASA grants.