Fig. 4. Averaged Icy Galilean Satellite Spectra.

Includes all spectra with 22\dmic\ \T_B\ warmer than 130^o K (Ganymede and Callisto) or 90^o K (Europa), for both spacecraft. The number in parentheses indicates the number of spectra in each average. All spectra have been smoothed with a boxcar filter of width 14 cm^-1. The lower quality of the Voyager 2 spectra is clearly seen. No unambiguous spectral features are visible: the features in the Voyager 2 Ganymede and Callisto spectra above 800 cm^-1 are clearly sytematic calibration errors, as they reproduce between the two satellites but were not seen by Voyager1. The arrows labelled `k_max' and `n_min' by the Europa average show the locations of water ice spectral features.
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