Radio emission from Uranus was discovered a few days before the closest approach of Voyager 2 with Uranus on January 24, 1986. The planetary radio astronomy experiment recorded several types of emissions in the frequency range 1--900 kHz; they differ by their spectral, temporal, and polarization characteristics. The analysis of the observations led us to distinguish two smooth radio components, one occurring in the lowest frequency range (SLF) from 20 kHz to 347 kHz, and the other one reaching the highest observed frequencies, i.e., 865 kHz (SHF). The SLF component is left-hand polarized when observed in the northern magnetic hemisphere and right-handed in the southern magnetic hemisphere, without polarization reversal from dayside to nightside. The SHF component is only observed in the nightside of Uranus, and it is left-hand polarized. Several bursty emissions were observed: some of them are broadband bursts and occur in the 78- to 750-kHz range (b-bursty), others are narrow-band bursts and occur in the 40- to 270-kHz range (n-bursty). The broadband bursts were observed at low magnetic latitudes of the spacecraft and mainly when it was in the southern magnetic hemisphere; their polarization is left-handed.

The narrow-band bursts were observed in the northern magnetic hemisphere and are not correlated with the magnetic latitude of the spacecraft; their polarization is right-handed. Sporadic bursts of short duration were observed mainly in the northern magnetic hemisphere with right-hand polarization. Two periodic events were observed, ahead of the inbound bow shock and inside the magnetosphere of Uranus. Very low frequency emissions at 1.2 and 20.4 kHz are also discussed; some of them are correlated with in situ phenomena. From the polarization study we deduce the possible source locations of the main components in the frame of our hypothesis. The source regions are characterized by the latitude and longitude of the footprints of the magnetic field lines through the source expressed in the Uranographic longitude system (ULS). The SLF source would be fixed in magnetic longitude at the northern magnetic pole in the range 13¿ULS<38¿, 26¿ULS<70¿, and 1.23U. The emission mode would be ordinary. The SHF and b-bursty components would be fixed in magnetic longitude at the southern magnetic pole. The SHF (at 300 kHz) would be in the range -52¿< latitudeULS<-44¿, 228¿ULS<256¿, and 1.77U. The b-bursty component would be located in a smaller region included in the SHF region in the range-48¿ULS<-45¿ and 233¿ULS<243¿. For both high-frequency components the emission mode would be extraordinary.¿ American Geophysical Union 1987