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C. B. Olkin (Lowell Observatory), W. Calvin (University of Nevada at Reno), A. S. Bosh (Boston University and Lowell Observatory)
From observations of Saturn recorded with the Space Telescope Imaging Spectrometer (STIS) on the Hubble Space Telescope, we have high SNR data of Saturn and its rings, yielding individual spectra from both the East and West ansae of the A, B and C rings as well as the Encke and Cassini divisions. For each of the observations (with the G750L and G430L gratings) the slit was aligned along the ring ansae. The slit width of 52 arcsec spans Saturn and both the ansae of Saturn’s rings simultaneously. We find no significant East-West differences between spectra of each ring feature. But we do find marked differences between the different rings and divisions. In particular, the C ring and Cassini Division appear much more grey than the A ring, B ring and Encke division, possibly indicating a population of smaller particles. We will present a comparison of the ring spectra to Rhea, Ganymede, and Callisto. We find that Ganymede provides a good match to the B ring in overall brightness and red slope (from ~0.33 um to 0.7 um). At wavelengths longer than ~0.8 um the A and B ring show a significant drop in reflectance not seen in the icy satellites. We will also compare the ring spectra to a combination of minerals and ices. Support for this program (GO-07314.01) was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.