THE EQUATORIAL BOUNDARY OF THE ULTRAVIOLET JOVIAN NORTH AURORA OBSERVED WITH MULTISPECTRAL HUBBLE-SPACE-TELESCOPE IMAGES

Multispectral observations of the far ultraviolet Jovian aurora with t he faint object camera (FOC) on board the Hubble Space Telescope are r eported. They are used to describe and compare the morphology and the mean brightness of the H-2 Lyman and Werner bands observed at 153, 125 , and 130 nm. It is shown that most of the emissions are confined insi de the 6 R(J) O-6-GSFC auroral oval and fill a large fraction of the p olar cap. During the similar to 50 hours time span of the observations following a very strong aurora, no bright are was observed along the oval mapping the 30 R(J) O-6 oval. Hydrogen emissions at 125 and 130 n m are observed down to 50 degrees N and somewhat below, a region not a ccessible to previous FOC observations at longer wavelengths. Temporal variations are also observed on timescales of hours to days.