ANALYSIS OF SMOOTH HIGH-FREQUENCY EMISSION AT NEPTUNE

We present a detailed study of the highest-frequency component of smoo th radio emission observed during the Voyager 2 encounter with Neptune in August 1989. This emission occurs during three distinct periods on August 24 and 25, 1989, in the frequency range of 550 to 900 kHz. By assuming straight-line propagation from sources of both fundamental an d second harmonic gyroemission, we perform a detailed analysis of the observed polarization of the emission. The data are most consistent wi th an L-O mode source in the north magnetic polar region, around 50 de grees W, 50 degrees N. A second possible source is in the north magnet ic polar region, around 270 degrees W, 50 degrees N. This source must emit in the R-X mode.