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Published February 23, 1984 | public
Journal Article

Uranus: microwave images


Observations of Uranus at wavelengths of 2 and 6 centimeters with the Very Large Array were made in 1980 and 1981. The resulting maps of brightness temperature show a subsolar symmetry at 2 centimeters but a near-polar symmetry at 6 centimeters. The 6-centimeter maps show an increase in temperature from equator to pole with some evidence for a warm "ring" surrounding the north pole. The disk-average temperatures (147 +/- 5 K and 230 +/- 6 K at 2 and 6 centimeters, respectively) are distinctly lower than recently reported values; these results suggest that the secular increase in temperature reported during the last 15 years has been reversed. The variations in brightness temperature probably reflect variations in ammonia abundance in the planet's atmosphere, but the mechanism driving these variations is still unclear.

Additional Information

© 1984 American Association for the Advancement of Science. 23 February 1984; Accepted 17 May 1984. We thank K. Noll, I. de Pater, and S. Gulkis for helpful discussions and M. Klein for providing his unpublished compilation of microwave observation. This research was supported in part by NASA grants NGR33015141, 953614, NSG7320, and NGL 05-002-003 and NSF grant AST 79-11806A01. The Very Large Array is part of the National Radio Astronomy Observatory, which is operated by Associated Universities, Inc., under contract with the National Science Foundation.

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