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F. Tosi (INAF-IFSI), VIMS Team
Acquisitions by the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft are arranged in "data cubes", that is, for every pixel of the image, the corresponding spectrum in the 0.35 - 5.1 \mum range is available. The power of this technique is therefore the combination of spatial and spectral information, which allows a spectral mapping of the investigated surfaces. Statistical methods, such as clustering methods, can be helpful in handling spatially distributed data depending on several variables. VIMS data are, by definition, multifactorial: in fact, for each pixel on the surface of the observed body, we define a set of variables, that are the spectral channels of the spectrometer. One clustering method is the G-mode method, which was originally developed by A. Coradini and A.I. Gavrishin (Coradini et al., 1977) in order to automatically classify lunar samples. Here the method allows to distinguish the most important spectral features, so that averages are performed on similar spectra with high confidence level, with the identification of reasonable homogeneous classes as a result. The first attempts of applying this method to the VIMS data were quite reassuring (see Tosi et al., 2004, 2005a,b). Here we present the results of the application of the G-mode method to a subset of the Phoebe, Iapetus and Hyperion infrared data acquired by VIMS during the first year of the Cassini nominal mission. Since one of the main goals of the mission is to identify the source of the black material coating the leading hemisphere of Iapetus, which is believed to be either Phoebe or Hyperion, the G-mode results can be taken into account in order to establish a reasonable correlation in this sense.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.