Limb brightening on Uranus: The visible spectrum, II
Abstract
New narrow-band (100 Å) photoelectric area-scanning photometry of the Uranus disk is reported. Observations were concentrated on the two strong CH 4 bands at λ 6190 and 7300 Å. Adjacent continuum regions at λ 6400 and 7500 Å were also measured for comparison. Both slit and pinhole scans were made in orthogonal directions. Disk structure in each waveband is apparent through lack of circular symmetry in the intensity distribution over the Uranus image. Polar brightening is especially prominent in the λ 7500-Å waveband. Coarse quantitative determinations of the true intensity distribution over the Uranus disk were made. For the λ 6190-Å CH 4 band, Uranus exhibits a disk of essentially uniform intensity except for a hint of polar brightening. For the λ 7300-Å CH 4 band, moderate limb brightening is apparent. Specifically, the true intensities at the center and limb of the planetary disk are approximately in the proportion 1:2. Extreme limb brightening, with a corresponding intensity ratio greater than 1:4, is not permitted by the observational data.
- Publication:
-
Icarus
- Pub Date:
- May 1978
- DOI:
- 10.1016/0019-1035(78)90173-2
- Bibcode:
- 1978Icar...34..355P
- Keywords:
-
- Astronomical Photometry;
- Limb Darkening;
- Planetary Atmospheres;
- Uranus (Planet);
- Astrometry;
- Electrophotometers;
- Light (Visible Radiation);
- Luminous Intensity;
- Methane;
- Radial Distribution;
- Spectra;
- PHOTOELECTRIC EMISSIONS;
- BRIGHTNESS;
- ALBEDO;
- SPECTRUM;
- LIGHT (VISIBLE RADIATION);
- ELECTROPHOTOMETRY;
- URANUS;
- ATMOSPHERE;
- LIMBS;
- RADIAL DISTRIBUTION