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B. E. Schaefer (Louisiana S. U.), D. Rabinowitz, S. Tourtellotte (Yale), W. Blickley (LSU)
SMARTS has the unique capability of nightly monitoring for entire observing seasons of small icy bodies in the outer Solar System. The result is that our group has very-well-sampled BVI light curves for Nereid, Sedna, and over a dozen Kuiper Belt Objects (KBOs) for one-three complete observing seasons. This data base is designed to measure rotation periods (especially long periods), opposition surges, and to seek secular variations. Obtaining such a comprehensive data set is impossible by the usual observing-run mode.
In the past, Nereid has been varying with amplitudes of up to a magnitude on the time scale of days for some observing seasons, while in other seasons Nereid has been essentially constant. This suggests that Nereid (with its high eccentricity and out-of-round shape in orbit around an oblate planet) might be chaotically rotating. But in the last decade, Nereid has been largely constant, except for a large opposition surge of 0.52 mag. Now, starting in June, Nereid is back to having significant variations, with amplitude of 0.25 mag on a time scale of 10 days.
The small planet (90377) Sedna was discovered November 14, 2003 by Brown, Trujillo, and Rabinowitz [2004] using the large-area Quest camera on the 48" Oschin Schmidt at Palomar. At 100 AU from the Sun, it is the most distant body known in the solar system and its presence at that location remains a mystery. It is also the largest known planet after Pluto. We have monitored the R-band rotational light curve and optical colors of Sedna for more than one year using the SMARTS 1.3m telescope and ANDICAM. Here we present our conclusions regarding a possible long rotation period, which could indicate the presence of an undetected satellite.
For over a dozen KBOs with long-term synoptic light curves, we generally find a low amplitude for the opposition surge. We also find that the opposition surge amplitude is independent from the color (for B, V, and I).
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.