Ultraviolet photometry from the Orbiting Astronomical Observatory. XIII. The albedo of Jupiter, Uranus, and Neptune.

This paper presents OAO-2 broad-band ultraviolet photometry data for Jupiter, Uranus, and Neptune. These data have been combined with observations of 23 late-type stars to derive planetary albedos over the region A. The new broad-band albedo for Jupiter agrees well with a previous measurement based on OAO-2 spectrometer data. The albedos for Uranus and Neptune are in good agreement with ground measurements in the region of overlap. The results for Uranus and Neptune have been compared with theoretical calculations for semi-infinite and finite pure H2 Rayleigh-Raman scattering atmospheres. Except for the shortest wavelengths, the measurements lie below the semi-infinite theoretical calculations. The calculations for the finite atmospheres suggest that an additional absorbing constituent will be needed to explain the observed albedos. Subject headings: atmospheres, planetary - Jupiter - Neptune - spectrophotometry - ultraviolet - Uranus