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 the faint object camera (FOC) on board the Hubble Space Telescope are reported. 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 inside the 6 R(J) O-6-GSFC auroral oval and fill a large fraction of the polar 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 nm are observed down to 50 degrees N and somewhat below, a region not accessible to previous FOC observations at longer wavelengths. Temporal variations are also observed on timescales of hours to days.