HR: 16:00h
AN: P44A-01 INVITED     [Abstracts]
TI: Cassini Ultraviolet Imaging Spectrograph Initial Observations of Saturn
AU: * Pryor, W R
EM: wayne\_pryor@centralaz.edu
AF: Central Arizona College, 8470 N. Overfield Rd., Coolidge, AZ 85228 United States
AU: West, R A
EM: robert.a.west@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Dr., Pasadena, CA 91109 United States
AU: Stewart, I A
EM: ian.stewart@lasp.colorado.edu
AF: LASP/University of Colorado, 1234 Innovation Dr., Boulder, CO 80303 United States
AU: Shemansky, D E
EM: dons@hippolyta.usc.edu
AF: Univ Southern California/Dept. of Aerospace Engineering, 854 West 36th Pl, Los Angeles, CA 90089 United States
AU: Ajello, J M
EM: jajello@mail1.jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Dr., Pasadena, CA 91109 United States
AU: Esposito, L W
EM: larry.esposito@lasp.colorado.edu
AF: LASP/University of Colorado, 1234 Innovation Dr., Boulder, CO 80303 United States
AU: Colwell, J E
EM: josh.colwell@lasp.colorado.edu
AF: LASP/University of Colorado, 1234 Innovation Dr., Boulder, CO 80303 United States
AU: McClintock, W E
EM: william.mcclintock@lasp.colorado.edu
AF: LASP/University of Colorado, 1234 Innovation Dr., Boulder, CO 80303 United States
AU: Jouchoux, A
EM: Alain.Jouchoux@lasp.colorado.edu
AF: LASP/University of Colorado, 1234 Innovation Dr., Boulder, CO 80303 United States
AU: Hansen, C J
EM: cj@frostrus.jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Dr., Pasadena, CA 91109 United States
AU: Crary, F J
EM: fcrary@swri.edu
AF: Southwest Research Institute, 6220 Culebra Rd, San Antonio, TX 78228 United States
AB: Cassini's Ultraviolet Imaging Spectrograph (UVIS) has begun making detailed studies of Saturn. Two long slit spectral channels are used to obtain EUV data from 56.3-118.2 nm and FUV data from 111.5-191.3 nm. 64 spatial pixels along each slit are combined with slit motion to build up spectral images of Saturn, with sufficient spatial resolution to reveal Saturn's auroral oval. Observed emissions include H Lyman-alpha and H2 bands from Saturn's auroras and dayglow. The auroral spectrum is remarkably similar to that of Jupiter, showing short-wavelength FUV absorption due to methane, CH4. Saturn's aurora is observed to vary in brightness by at least a factor of four. The brightest auroral emissions seen so far occurred after 2004 day 207 19:30 when Cassini CAPS recorded passage of a solar wind shock. The enhanced auroral brightness persisted for days, and is seen at both poles of Saturn. Saturn's auroral and dayglow spectrum show striking differences. At the longest wavelengths, Saturn's reflected sunlight spectrum is strongly modulated by absorption bands of acetylene, C2H2. Maps of the distribution of C2H2 will provide clues to Saturn's upper atmospheric circulation.
DE: 5704 Atmospheres--composition and chemistry
DE: 5737 Magnetospheres (2756)
DE: 6275 Saturn
DE: 2704 Auroral phenomena (2407)
DE: 0305 Aerosols and particles (0345, 4801)
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting