PHOTOELECTRIC PHOTOMETRY OF SATURNíS RINGS: A PROPOSED PROJECT FOR 2003-2004


2002



A team consisting of Walter Haas, Julius Benton, and Fred Pilcher of the A.L.P.O. have formed an observing project as a subset of the regular programs of the A.L.P.O. Saturn Section to do photoelectric photometry of Saturnís rings. This is a strategy to improve observations to detect and quantify the curious Bicolored Aspect of Saturnís Ring A pursuant to the article written by Thomas A. Dobbins, Alan Heath, and Valeri Dikarev entitled "Saturnís Colorful Mystery" in the December 2002 issue of Sky and Telescope magazine. The A.L.P.O. Saturn Section project would monitor extremely small brightness fluctuations in different wavelengths at various position angles around Saturnís ring system. The technique suggested by Haas, Benton, and Pilcher would involve the use of old-style photoelectric photometers of the 1970ís or early 1980ís vintage, and an aperture of roughly 1.0 to 2.0 arcseconds. The technique would use the standard Johnson UBV filter set (or perhaps just B and V), perhaps supplemented with other standard filters such as the Kron R and G filters. Applied to Saturnís rings, this would admit the large amount of light required for very precise magnitude measurements. Observations at 10 to 15 degree intervals in position angle all the way around Ring A, calibrated with Ring B measurements, would be repeated at time intervals of 20 to 40 minutes on a single night. Such measurements should capture any progressive changes in the rings with the revolution of Saturn of conjectured underlying structures. Routine observations of this kind throughout several observing seasons (or apparitions) should provide quantitative information, currently lacking, which theorists need for model building. The greatest difficulty is that photoelectric photometers have largely been replaced by CCD photometers due to their relative ease of use, but the latter are also inherently less accurate. The A.L.P.O. team is trying to locate observers who have older photoelectric photometers who would be interested in participating in this long term project, slated to begin with the 2003-2004 apparition of Saturn (which begins soon after Saturn emerges from conjunction with the Sun on June 24, 2003). It is believed that there may also be professional and/or university observatories who possess top-of-the-line photoelectric photometers left over from the 1970í2 or 1980ís that could be brought back into use. More developments shall be forthcoming on this project, but observers who are adequately equipped are encouraged to join the team for the 2003-3004 apparition of Saturn. All inquiries should be addressed to the A.L.P.O. Saturn Section at the following address: Julius L. Benton, Jr., Ph.D. Coordinator - A.L.P.O. Saturn Section c/o ASSOCIATES IN ASTRONOMY P.O. Box 30545 Wilmington Island Savannah, GA 31410 USA Telephone: 912-897-0951 Cellular: 912-661-3924 E-Mail: jlbaina@msn.com Website: http://www.lpl.arizona.edu/alpo/sat.html eGroups: Saturn-ALPO@yahoogroups.com




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