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

✍ Scribed by Imke de Pater; Mark R. Showalter; Jack J. Lissauer; James R. Graham

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 214 KB
• Volume: 121
• Category: Article
• ISSN: 0019-1035
• DOI: 10.1006/icar.1996.0078

✦ Synopsis

main rings are viewed edge-on and so reflect very little sunlight toward Earth. In this note, we discuss the first ground-based detection of Saturn's We report the first ground-based detection of Saturn's G G ring and the first infrared images of the E ring. ring, together with the first infrared images of the E ring. The 2. Observations and Results. We observed Saturn on UT 1995 May data were taken during the May and August 1995 ring plane 21-23 and 1995 August 9-11 using the 10-m W. M. Keck telescope crossings using the W. M. Keck telescope at a wavelength of on Mauna Kea, Hawaii. 1 We used the facility's near-infrared camera

2.26 m. The E ring's radial and vertical structure is found to (Matthews and Soiffer 1994), which is equipped with a Santa Barbara be generally consistent with previous results from Voyager and Research Corporation InSb array (256 by 256 pixels; the pixel size is Earth-based observatories; it has a brightness peak near the 0.151 arcsec). The observations were carried out with a narrow-band orbit of Enceladus and extends outward to ȁ6 R S (Saturn radii). filter centered at a wavelength ϭ 2.26 Ȑm (2.233-2.286 Ȑm), which The E ring is ȁ40% fainter at 2.26 m than in the visual, falls in a methane absorption band. Sunlight, usually reflected by Saturn's thick cloud layers, is absorbed at this wavelength by methane gas above confirming and extending previous reports that it is very blue Saturn's cloud layers, making the planet very dark. The observations in color. The G ring is located at 2.8 R S and is unresolved in described in this note were taken on May 23, just after Earth's first vertical thickness. Its reflected intensity is similar to that found crossing of Saturn's ring plane, and on August 10, several hours before in the comparable Voyager image, implying that the ring is the second crossing. Thus the main rings were nearly edge-on, and the neutral in color from the visual to the infrared.