Keck Infrared Observations of Saturn's E and G Rings during Earth's 1995 Ring Plane Crossings

Abstract

We report the first ground-based detection of Saturn's G ring, together with the first infrared images of the E ring. The data were taken during the May and August 1995 ring plane crossings using the W. M. Keck telescope at a wavelength of 2.26 μm. The E ring's radial and vertical structure is found to be generally consistent with previous results from Voyager and Earth-based observatories; it has a brightness peak near the orbit of Enceladus and extends outward to ∼6RS(Saturn radii). The E ring is ∼40% fainter at 2.26 μm than in the visual, confirming and extending previous reports that it is very blue in color. The G ring is located at 2.8RSand is unresolved in vertical thickness. Its reflected intensity is similar to that found in the comparable Voyager image, implying that the ring is neutral in color from the visual to the infrared.