High-precision photometry of extreme kbo 2003 EL61

Abstract

We present high-precision, time-resolved, visible and near-infrared photometry of the large (diameter 2500 km) Kuiper belt object (136108) 2003 EL61. The new data confirm rapid rotation at period P = 3.9155 0.0001 h with a peak-to-peak photometric range of ΔmR = 0.29 0.02 mag and further show subtle but reproducible color variations with rotation. Rotational deformation of 2003 EL61 alone would give rise to a symmetric light curve free of color variations. The observed photometric deviations from the best-fit equilibrium model show the existence of a large surface region with an albedo and color different from the mean surface of 2003 EL61. We explore constraints on the nature of this anomalous region set by the existing data. © 2008. The American Astronomical Society. All rights reserved.