A new VLT surface map of Titan at 1.575 microns

Free access article

Issue		A&A Volume 421, Number 1, July I 2004


Page(s)		L17 - L20
Section		Letters
DOI		http://dx.doi.org/10.1051/0004-6361:20040171

A&A 421, L17-L20 (2004)
DOI: 10.1051/0004-6361:20040171

Letter

A new VLT surface map of Titan at 1.575 microns

M. Hartung¹, T. M. Herbst², L. M. Close³, R. Lenzen², W. Brandner², O. Marco¹ and C. Lidman¹

¹ European Southern Observatory, Alonso de Cordova 3107, Santiago 19, Chile
² Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
³ Steward Observatory, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721-0065, USA

(Received 15 April 2004 / Accepted 12 May 2004)

Abstract
We present a first high contrast 1.575 micron surface map of Titan, that is haze corrected by simultaneously imaging the stratospheric layer. At visible and most near-infrared wavelengths, the methane rich atmosphere completely obscures the surface; only in a few narrow wavelength windows does the atmosphere become optically thin. One of the most convenient windows (Griffth et al. 2003) lies at 1.58 $\mu$ m, adjacent to the methane absorption feature at 1.62 $\mu$ m. Our data span seven consecutive nights, resulting in phase coverage of 275° in longitude. The images were taken with NAOS-CONICA adaptive optics system at the VLT, using the recently commissioned Simultaneous Differential Imager mode (SDI). The combination of adaptive optics and simultaneous imaging through three filters sampling the methane absorption at 1.6 micron reveals extraordinary details of Titan's surface. Providing views of Titan's surface at high resolution (60 mas) is of particular topical importance, since the Cassini-Huygens mission is currently approaching the Saturn system and the Huygens probe will enter Titan's atmosphere in early 2005.

Key words: planets and satellites: individual: Titan -- infrared: solar system -- instrumentation: adaptive optics

Offprint request: M. Hartung, mhartung@eso.org

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