KORONIS FAMILY - REFLECTANCE SPECTRA OF 243 IDA, 1442 CORVINA AND 2226 CUNITZA

Low-resolution spectra of the asteroids 243 Ida (target of the Galileo spacecraft on 28 August 1993), 1442 Corvina and 2226 Cunitza (other m embers of the Koronis family) were obtained. In the frame of a ground- based international campaign to observe Ida before the Galileo encount er (Binzel et al., Icarus, in press, 1993), we observed it spectroscop ically in the visible at ESO-La Silla (Chile), obtaining four spectra covering the total rotational period (4.63 h). In one of these spectra , we observed a considerable variation in the depth of the absorption feature near 0.9 mum, implying a different content of pyroxene and oli vine on the surface of Ida. The spectra obtained for the other two obj ects are consistent with those of S-type asteroids and similar to that of Ida.