Jovian UV Albedo and Center-to-Limb Profiles as Observed by IUE and WFPC2

M. B. Vincent, J. T. Clarke, G. E. Ballester (U. Michigan), W. M. Harris (U. Wisconsin), T. Livengood (UMD at NASA/GSFC)

Jupiter's ultraviolet albedo and center-to-limb profiles vary with latitude and wavelength as derived from observations by the International Ultraviolet Explorer (IUE) and the Hubble Space Telescope's Wide Field and Planetary Camera 2 (WFPC2). This study combines the complimentary feature of both instruments to examine these variations. WFPC2 images, from May 1994 through March 1997, provide the high spatial resolution required to accurately determine the center-to-limb profiles. However, the broad band WFPC2 UV filters limit our ability to identify individual photoabsorbing species. IUE's short and long wavelength cameras provide spectral resolution, at the expense of spatial resolution. In September 1995 and August 1996, IUE observed the darker belt near tex2html_wrap_inline13 and the brighter zone near tex2html_wrap_inline15 planetocentric latitude. Multiple central meridian offsets were targeted to obtain the wavelength dependence of the center-to-limb profile. The target areas were based on WFPC2 images convolved to match IUE's point spread function. All IUE observations used the small apertures. One of the IUE results shows the center- to-limb profiles change significantly from 170 to 198 nm and more gradually up to 335 nm, with strongest limb darkening occurring at the shortest wavelengths. This work is supported by NASA grant NAGW-5235 and grant AR05797.01-94A from the STSCI to the University of Michigan.