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M. Hirtzig, A. Coustenis (LESIA, Obs. de Paris-Meudon, France), O. Lai (CFHT, Hawaii, USA and LESIA), M. Combes, E. Gendron, D. Gratadour (LESIA, Obs. de Paris-Meudon, France), T. Fusco, L. Mugnier (ONERA, Châtillon, France), P. Rannou (S. A., Univ. Paris 6 - Univ. de Versailles, France), A. Negrão (S. A., Univ. Paris 6 - Univ. de Versailles, France and LESIA), S. Lebonnois (LMD, Paris), E. Bratsolis (E.N.S.T., France)
We have acquired new images of Titan in 2002 using the CFHT adaptive optics system PUEO, in Hawaii. With the infrared camera KIR, we have covered the 0.8-2.5 micron range on Titan using narrow-band filters during four nights in November 2002 (covering both the GEE and the GWE with seeing less than 0.6") thus gathering very good resolution data on Titan's disk. As described in Coustenis et al. (2001), atmospheric images usually show the South hemisphere brighter than the North, but in December 2001, this asymmetry was reversed in our FeII (1.64 micron) and Kcont (2.26 micron) stratospheric filters. This phenomenon was following the ``loss of the smile" (Lorenz, 2001), and it is still at work in 2002, at lower altitudes, as visible at 2.16 (BrGamma), 1.64 (FeII) and 1.18 (J2) micron. Another new feature is observed at 2.12 micron: a stable bright spot (about 0.1 arcsec large) moves close to the South Pole. This feature could be indicative of an atmospheric phenomenon (cloud tracer or perhaps a ``vortex") or - more unlikely, but the filter does probe the ground - a surface feature (polar cap?). As for the surface of Titan, we find the equatorial spot to be bright again in all the near-infrared filters investigated and at the position expected with respect to the orbital phase. Since we have observed at consecutive nights around both the greatest elongations, we intend to monitor these features and to check the bright zones found on the trailing hemisphere of Titan (Combes et al., 1997). This study is combined with that of VLT/NACO Titan data (Gendron et al., 2003) to be presented in another paper (Coustenis et al.). References: Coustenis et al. (2001) Icarus 154, 501; Coustenis et al., (2003), in preparation; Gendron et al., (2003), A&A, in press; Lorenz et al (2001), Geoph. Res. Letters 28, 4453.
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The author(s) of this abstract have provided an email address for comments about the abstract: Athena.Coustenis@obspm.fr
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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.