Spatially resolved absolute spectrophotometry of Saturn: 3390 to 8080 Å

Abstract Absolute spectrophotometry of four regions on the visible disk of Saturn (north and south polar regions, equatorial band, south “temperate” region) from 3390 to 8080 A is reported. Spectral resolution is 10 A in the interval 3390–6055 A, and 20 A; aperture size is 1.92 arcsec. The explicit purpose of our observations was to provide ground-based photometric calibration for the Pioneer Saturn Imaging Photopolarimeter (IPP). We also compare our data with earlier spectrophotometric measurements of Saturn ( R.L. Younkin and G. Munch, 1963 ,Mem. Soc. Roy. Sci. Liege 7, 123–136; W.M. Irvine and A.P. Lane, 1971 ,Icarus 16, 10–26; T.B. McCord, T.V. Johnson, and J.H. Elias, 1971 ,Astrophys. J. 165, 413–424) and with the M. Podolak and R.EE. Danielson (1977) Icarus 30, 479–492) parameterization of “Axel Dust.” The latter reproduces the broad features but not the details of the observed spectral reflectivity (I/F). We find that large depths of clear molecular hydrogen (>14 km-am in the temperate regions) are needed to match the observed upturn in reflectivity shortward of 3800 A.

[1]  W. Irvine,et al.  Monochromatic Albedos for the Disk of Saturn , 1971 .

[2]  J. Hansen,et al.  Jupiter's Atmospheric Composition and Cloud Structure Deduced from Absorption Bands in Reflected Sunlight , 1978 .

[3]  W. Macy.  Inhomogeneous models of the atmosphere of Saturn , 1977 .

[4]  Lawrence P. Giver,et al.  Intensity measurements of the CH4 bands in the region 4350 A to 10,600 A , 1978 .

[5]  L. Lebofsky,et al.  Laboratory reflection spectra for the determination of chemical composition of icy bodies , 1976 .

[6]  J. Caldwell.  The atmosphere of Saturn - An infrared perspective , 1977 .

[7]  J. Martonchik.  Sulfuric acid cloud interpretation of the infrared spectrum of Venus , 1974 .

[8]  T. McCord,et al.  Saturn and its satellites - Narrow-band spectrophotometry, 0.3-1.1 micron , 1971 .

[9]  D. W. Latham,et al.  A rediscussion of the atmospheric extinction and the absolute spectral-energy distribution of Vega. , 1975 .

[10]  J. Caldwell.  Ultraviolet observations of Mars and Saturn by the TDIA and OAO-2 satellites , 1977 .

[11]  M. Tomasko,et al.  Photometry and polarimetry of Jupiter at large phase angles: I. Analysis of imaging data of a prominent belt and a zone from pioneer 10 , 1978 .

[12]  G. Orton,et al.  Spatially resolved absolute spectral reflectivity of Jupiter: 3390–8400 Å , 1975 .

[13]  R. E. Danielson,et al.  Axel dust on Saturn and Titan , 1977 .

[14]  H. C. Van De Hulst,et al.  Multiple light scattering in planetary atmospheres. , 1968 .

[15]  J. B. Oke.  Photoelectric Spectrophotometry of Stars Suitable for Standards. , 1964 .

[16]  R. N. Strickland,et al.  Imaging Photopolarimeter on Pioneer Saturn , 1980, Science.

[17]  R. N. Griffin,et al.  Determination of extraterrestrial solar spectral irradiance from a research aircraft. , 1969, Applied optics.