1. For a description of the PWS instrument, see F. L. Scarf and D. A. Gurnett, Space Sci. Rev. 21, 289 (1977).
2. Possible magnetospheric radio emissions from Uranus were reported by L. W. Brown [Astrophys. J. 207, L209 (1976)], who used data from an earth orbiting spacecraft.
3. J. W. Warwick et al., Science 233, 102 (1986).
4. D. A. Gurnett, J. Geophys. Res. 80, 2751 (1975); W. S. Kurth, D. A. Gurnett, R. R. Anderson, ibid. 86, 5519 (1981).
5. J. W. Warwick et al., Science 204, 995 (1979).
6. D. A. Gurnett, W. S. Kurth, F. L. Scarf, ibid 212, 235 (1981).
7. ______, Nature (London) 292, 733 (1981).
8. F. L. Scarf et al.,Science 215, 587 (1982).
9. D. A. Gurnett and L. A. Frank, J. Geophys. Res. 81, 3875 (1976); D. Jones, Nature (London) 260, 686 (1976); D. B. Melrose, J. Geophys. Res. 86, 30 (1981).
10. N. F. Ness et al., Science 233, 85 (1986).
11. F. L. Scarf et al., J. Geophys. Res. 76, 5162 (1971).
12. F. L. Scarf, D. A. Gurnett, W. S. Kurth, Science 204, 991 (1979).
13. H. S. Bridge et al., ibid, 233, 89 (1986).
14. R. M. Thorne et al., J. Geophys. Res. 78, 1581 (1973).
15. R A. Helliwell, Whistlers and Related Ionospheric Phenomena (Stanford Univ. Press, Stanford, CA, 1965), p. 207; F. F. Coroniti et al., Geophys. Res. Lett. 7, 45 (1980).
16. C. F. Kennel and H. E. Petschek, J. Geophys. Res. 71, 1 (1966).
17. S. M. Krimigis et al., Science 233, 97 (1986).
18. A. L. Broadfoot et al., ibid., p. 74.
19. C. F. Kennel et al., J. Geophys. Res. 75, 6136 (1970).
20. D. A. Gurnett et al., Icarus 53, 236 (1983).
21. H. Fechtig, E. Grun, J. Kissel in Cosmic Dust, J. A. M. McDonnell, Ed. (Wiley, New York, 1978), p. 607.
22. We thank the Voyager team at the Jet Propulsion Laboratory and the staff at NASA Headquarters for their valuable support; E. Miner for his efforts in scheduling the broadband coverage and J. Anderson, C. Avis, and the staff of the Multimission Image Processing Laboratory for their assistance with the broadband data processing, N. Toy and the General Science Data Team for timely and efficient production of quick-look data products; the Planetary Data System for the use of its facilities; the Space Physics Analysis Network for the use of its facilities in communicating data between the University of Iowa and the Jet Propulsion Laboratory; S. Chang, K Jordan, R. Brechwald, L. Granroth, J. Cook-Granroth, and R. Kraemer for programming support; N. Ness, S. M. Krimigis, H. Bridge, and J. Warwick for their helpful discussions and data comparisons. We also remember C. Stembridge for his dedication to the excellence of the Voyager mission and his continual support of the PWS investigation. The research at the University of Iowa was supported by NASA through contract 954.013 with the Jet Propulsion Laboratory, by grants NGL-16-001-043 and NGL-16-001-002 with NASA Headquarters, by the Office of Naval Research through contract N00014-85-K-040, and by the State of Iowa through a faculty development assignment (to D.A G.). The research at TRW was supported by NASA through contract 954012 with the Jet Propulsion Laboratory.
31 March 1986, accepted 5 May 1986