SPECTRAL OBSERVATIONS OF IMPACT DARK SPOTS

We carried out a spectral observation of traces of the comet impacts w ithin the wavelength region between 440 and 830 nm. Three dark spots o f fragments K, E, and G impact sites were investigated. The spectrum o f these dark spots shows no special emission or absorption lines in th is observation. The global spectral feature resembles that of Jovian z one cloud rather than that of the belt. While the continuum reflectivi ty of the dark spots of K and E sites is less than 0.42 at 600 nm, tha t of the G site is 0.33. These values should be interpreted as an uppe r limits because of the influence of atmospheric seeing. The equivalen t width of the absorption lines at the K sites is also derived. Both t he continuum reflectivity and the equivalent width of the dark spots a re smaller than those of any Jovian zonal cloud. This indicates that t he dark spots ale low-albedo cloud formed at the upper atmosphere.