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Science 15 December 1989:
Vol. 246. no. 4936, pp. 1498 - 1501
DOI: 10.1126/science.246.4936.1498
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Articles

Voyager Planetary Radio Astronomy at Neptune

James W. Warwick 1, David R. Evans 1, Gerard R. Peltzer 1, Robert G. Peltzer 1, Joseph H. Romig 1, Constance B. Sawyer 1, Anthony C. Riddle 2, Andrea E. Schweitzer 3, Michael D. Desch 4, Michael L. Kaiser 4, William M. Farrell 4, Thomas D. Carr 5, Imke de Pater 6, David H. Staelin 7, Samuel Gulkis 8, Robert L. Poynter 8, André Boischot 9, Françoise Genova 9, Yolande Leblanc 9, Alain Lecacheux 9, Bent M. Pedersen 9, and Philippe Zarka 9

1 Radiophysics, Inc., Boulder, CO 80301
2 Cooperative Institute for Research in the Environmental Sciences, Boulder, CO 80309
3 Department of Physics, Pomona College, Pomona, CA 91711
4 Laboratory for Extraterrestrial Physics, Goddard Space Flight Center, Greenbelt, MD 20771
5 Department of Astronomy, University of Florida, Gainesville, FL 32611
6 Astronomy Department, University of California, Berkeley, CA 94720
7 Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02319
8 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109
9 Observatoire de Paris, Section d'Astrophysique, 92190 Meudon, France

Detection of very intense short radio bursts from Neptune was possible as early as 30 days before closest approach and at least 22 days after closest approach. The bursts lay at frequencies in the range 100 to 1300 kilohertz, were narrowband and strongly polarized, and presumably originated in southern polar regions ofthe planet. Episodes of smooth emissions in the frequency range from 20 to 865 kilohertz were detected during an interval of at least 10 days around closest approach. The bursts and the smooth emissions can be described in terms of rotation in a period of 16.11 ± 0.05 hours. The bursts came at regular intervals throughout the encounter, including episodes both before and after closest approach. The smooth emissions showed a half-cycle phase shift between the five episodes before and after closest approach. This experiment detected the foreshock of Neptune's magnetosphere and the impacts of dust at the times of ring-plane crossings and also near the time of closest approach. Finally, there is no evidence for Neptunian electrostatic discharges.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Hubble Space Telescope Imaging of Neptune's Cloud Structure in 1994.
H. B. Hammel, G. W. Lockwood, J. R. Mills, and C. D. Barnet (1995)
Science 268, 1740-1742
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Latitudinal and Longitudinal Oscillations of Cloud Features on Neptune.
L. A. SROMOVSKY (1991)
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Interior Structure of Neptune: Comparison with Uranus.
W. B. Hubbard, W. B. HUBBARD, W. J. NELLIS, A. C. MITCHELL, N. C. HOLMES, S. S. LIMAYE, and P. C. MCCANDLESS (1991)
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High Winds of Neptune: A Possible Mechanism.
V. E. SUOMI, S. S. LIMAYE, and D. R. JOHNSON (1991)
Science 251, 929-932
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Atmospheric Dynamics of the Outer Planets.
A. P. Ingersoll and A. P. Ingersoll (1990)
Science 248, 308-315
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Voyager 2 at Neptune: Imaging Science Results.
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Magnetic Fields at Neptune.
N. F. Ness, M. H. Acuna, L. F. Burlaga, J. E. P. Connerney, R. P. Lepping, and F. M. Neubauer (1989)
Science 246, 1473-1478
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Hot Plasma and Energetic Particles in Neptune's Magnetosphere.
S. M. Krimigis, T. P. Armstrong, W. I. Axford, C. O. Bostrom, A. F. Cheng, G. Gloeckler, D. C. Hamilton, E. P. Keath, L. J. Lanzerotti, B. H. Mauk, et al. (1989)
Science 246, 1483-1489
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First Plasma Wave Observations at Neptune.
D. A. Gurnett, W. S. Kurth, R. L. Poynter, L. J. Granroth, I. H. Cairns, W. M. Macek, S. L. Moses, F. V. Coroniti, C. F. Kennel, and D. D. Barbosa (1989)
Science 246, 1494-1498
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