Abstract
New narrow-band (100 Å) photoelectric slit scan photometry of Uranus has been obtained in the spectral region 6000 to 8500 Å. Coarse radial intensity profiles in seven wavebands are presented. Measurements of the point spread function have been used to partially remove the effects of atmospheric seeing. Restoration of the Uranus image, with a spatial resolution limit ∼0″.5 arc, has been achieved by means of analytical Fourier-Bessel inversion. Results of the investigation confirm earlier studies of limb brightening on the Uranus disk. But not all strong CH 4 absorption bands are found to exhibit limb brightening. Specifically, the CH 4 bands at 8000 and 8500 Å show pronounced apparent limb darkening. Polar brightening may be responsible for the phenomenon. If so, an aerosol haze with a local optical thickness ∼0.5 or greater would be required. Visibility of the dense cloud layer located deep in the atmosphere might also cause apparent limb darkening. If so, the maximum permitted [CH 4/H 2] mixing ratio in the visible atmosphere would correspond to ∼3 times the solar value.
Published Version
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