Aperture synthesis observations of Saturn and its rings at 2.7-mm wavelength |
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| Institution: | 1. SETI Institute, 339 Bernardo Ave, Mountain View, CA 94043, USA;2. NASA Ames Research Center, Mail-Stop 244-11, Moffett Field, CA 94035, USA;3. Gural Software and Analysis LLC, 12241 Eliza Court, Lovettsville, VA 20180, USA;4. CAMS BeNeLux, Am Ollenkamp 4, D 48599 Gronau, Germany;5. CAMS Chile, Cerro Tololo Inter-American Observatory, NSF''s National Optical-Infrared Astronomy Research Laboratory, Casilla 603, La Serena, Chile;6. Dep. of Physics and Astronomy, University of Central Arkansas, 201 Donaghey Ave, Conway, AR 72035, USA;7. LOCAMS, Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001, USA;8. CAMS New Zealand, Dept. of Physics & Astronomy, University of Canterbury, Christchurch 8140, New Zealand;9. Mendocino College, 1000 Hensley Creek Road, Ukiah, CA 95482, USA;10. CAMS Turkey, Yozgat Bozok University, Department of Physics, 66100 Yozgat, Turkey;11. CAMS Texas, 4635 Shadow Grass Dr., Katy, TX 77493, USA;12. CAMS South Africa, 258 Ninth Road, Bredell 1623, Kempton Park, South Africa;13. CAMS EXOSS, Observatorio Nacional, Rua Gal. José Cristino 77, Rio de Janeiro, RJ 20921-400, Brazil;14. CAMS Australia, Space Science and Technology Centre, Curtin University, Perth, WA 6102, Australia;15. CAMS Namibia, High Energy Stereoscopic System Experiment, Windhoek 11009, Namibia;p. CAMS Florida, Gainesville, FL 32605, USA;q. CAMS Chile, STAR Institute, University of Liège, B-4000 Liège 1, Belgium;r. CAMS Arkansas, North Little Rock, AR 72118, USA;s. College of Central Florida, 3001 SW College Road, Ocala, FL 34474-4415, USA;u. UACN, International Astronomical Center, P.O. Box 224, Abu Dhabi, United Arab Emirates;v. Embry-Riddle Aeronautical University, 3700 Willow Creek Road, Prescott, AZ 86301, USA;w. Bindoon, WA 6502, Australia;x. Department of Geology, University of Otago, P. O. Box 56, Dunedin 9054, New Zealand;y. CAMS Turkey, Ege University, Faculty of Science, Department of Physics, 35100 Bornova, Izmir, Turkey;z. IMCCE, Observatoire de Paris - PSL, 77 av. Denfert-Rochereau, 75014 Paris, France;11. Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA |
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| Abstract: | We present 2.7-mm interferometric observations of Saturn made near opposition in June 1984 and June 1985, when the ring opening angle was 19° and 23°, respectively. By combining the data sets we produce brightness maps of Saturn and its rings with a resolution of 6″. The maps show flux from the ring ansae, and are the first direct evidence of ring flux in the 3-mm wavelength region. Modelfits to the visibility data yield a disk brightness temperature of 156 ± 5°K, a combined A, B, and C ring brightness temperature of 19 ± 3°K, and a combined a ring cusp (region of the rings which block the planet's disk) brightness temperature of 85 ± 5°K. These results imply a normal-to-the-ring optical depth for the combined ABC ringof 0.31 ± 0.04, which is nearly the same value found for wavelenghts from the UV to 6 cm. About 6°K of the ring flux is attributed to scattered planetary emission, leaving an intrinsic thermal component of ∼13°K. These results, together with the ring particle size distributions found by the Voyager radio occultation experiments, are consistent with the idea that the ring particles are composed chiefly of water ice. |
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