Observations of Uranus occultation events

Abstract

A PRELIMINARY analysis of photometric data obtained by Zellner at the Perth Observatory during the Uranus appulse to SA0 158687 on 10 March 1977 shows at least three brief occultation events which appear to coincide with portions of a Uranian ring system reported by Elliot et al.1. No occultation by Uranus itself occurred at Perth. Our group also obtained an observation by Smith with a portable telescope from the vicinity of Mauritius. The data are marginal due to variable transparency but it seems clear that there was no occultation by Uranus which diminished the stellar intensity by more than 50%. No ring events were observed from Mauritius due to the onset of a rain shower. Our observations at Perth, along with the null result from Mauritius, can be combined with other available data2–5 to improve the deduction of the geometry of the ring features, and to obtain a preliminary upper limit to the radius of Uranus.