A Search for Rings, Moons, or Debris in the Pluto System during the 2006 July 12 Occultation

Abstract

We examined our data runs from four sites for the 2006 July 12 occultation of the star P384.2 (McDonald & Elliot, AJ 120, 1599, 2000; UCAC2 26039859), to search for moons, rings, or other debris in the Pluto system. Our data runs extended 80 minutes, or 115,200 km. Motivated by the discovery of P1 (Hydra) and P2 (Nix), each approximately 50 km in diameter and thought to result from the same collision that formed Charon, S. A. Stern et al. (Nature 439, 946-948, 2006) suggested that such matter might be detectable. Though their first estimate was unobservably low at 5×10-6, it could change by a factor of 10,000 or more in either direction (Stern, private communication). Our cloudless data sets, in declining order of S/N, used our Portable Occultation, Eclipse, and Transit Systems (POETS; Souza et al., in preparation) and include those from the 2.3-m ANU telescope at Siding Spring, Australia; 0.8-m Black Springs telescope near Adelaide, and the 1.8-m EOS telescope at Mt. Stromlo; though the atmospheric observation time at the 1-m Mt. Canopus Telescope at Hobart could be recovered from the comparison stars, cloudy intervals prevent full recovery during the ring/debris possible interval. Our observing with the 1-m Mt. John University Observatory in New Zealand was rendered impossible by the lack of electricity resulting from a major snowstorm. For the ring/debris search, we also evaluated data from past Pluto (Pasachoff et al., AJ 129, 1718-1723, 2005) and Charon (Gulbis et al., Nature 439, 48-51, 2006) occultations. See also Elliot et al. and Gulbis et al. (this meeting).