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Originally published in Science Express on 16 December 2004
Science 25 February 2005:
Vol. 307. no. 5713, pp. 1255 - 1259
DOI: 10.1126/science.1105356
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Reports

Radio and Plasma Wave Observations at Saturn from Cassini's Approach and First Orbit

D. A. Gurnett,1* W. S. Kurth,1 G. B. Hospodarsky,1 A. M. Persoon,1 T. F. Averkamp,1 B. Cecconi,1 A. Lecacheux,2 P. Zarka,2 P. Canu,3 N. Cornilleau-Wehrlin,3 P. Galopeau,3 A. Roux,3 C. Harvey,4 P. Louarn,4 R. Bostrom,5 G. Gustafsson,5 J.-E. Wahlund,5 M. D. Desch,6 W. M. Farrell,6 M. L. Kaiser,6 K. Goetz,7 P. J. Kellogg,7 G. Fischer,8 H.-P. Ladreiter,8 H. Rucker,8 H. Alleyne,9 A. Pedersen10

We report data from the Cassini radio and plasma wave instrument during the approach and first orbit at Saturn. During the approach, radio emissions from Saturn showed that the radio rotation period is now 10 hours 45 minutes 45 ± 36 seconds, about 6 minutes longer than measured by Voyager in 1980 to 1981. In addition, many intense impulsive radio signals were detected from Saturn lightning during the approach and first orbit. Some of these have been linked to storm systems observed by the Cassini imaging instrument. Within the magnetosphere, whistler-mode auroral hiss emissions were observed near the rings, suggesting that a strong electrodynamic interaction is occurring in or near the rings.

1 Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA.
2 Observatoire de Paris, 92195 Meudon, France.
3 Centre d'Etude des Environments Terrestre et Planétaires (CETP)–L'Institut Pierre-Simon La Place, 78140 Velizy, France.
4 Centre d'Etude Spatiale des Rayonnements–CNRS, 31028 Toulouse, France.
5 Swedish Institute of Space Physics, SE-751 21 Uppsala, Sweden.
6 NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
7 Department of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA.
8 Austrian Academy of Sciences, Space Research Institute, A-8042 Graz, Austria.
9 Department of Automatic Control and Systems Engineering, University of Sheffield, Sheffield S1 4DU, UK.
10 Department of Physics, University of Oslo, Blindern, N-0316 Oslo, Norway.

* To whom correspondence should be addressed. E-mail: donald-gurnett{at}uiowa.edu

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