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O. Groussin (LAS), S. Peschke (ESA), P.L. Lamy (LAS)
We present the analysis of new observations of 2060 Chiron with the Infrared Space Observatory (ISO). They were performed with the ISO photometer (ISOPHOT) from 8 to 15 June 1996, when Chiron was near perihelion at a heliocentric distance of 8.46 AU, using four filters centered at 25, 60, 100 and 160~\mum. The observed fluxes are fitted to a thermal model which considers a mixture of water ice and refractory materials on the surface and includes heat conduction into the interior of the nucleus. We derive a thermal inertia of 10~JK-1m-2s-1/2. Combining the present IR data with visible observations by Luu (1990) and Marcialis (1993), we determine a radius of 80±10~km and a geometric albedo of 0.14±0.02.