@article{d84c8d211b2242b2ba9e9168ccff6a4f,
title = "Radar and infrared observations of binary near-Earth Asteroid 2002 CE26",
abstract = "We observed near-Earth Asteroid (NEA) 2002 CE26 in August and September 2004 using the Arecibo S-band (2380-MHz, 12.6-cm) radar and NASA's Infrared Telescope Facility (IRTF). Shape models obtained based on inversion of our delay-Doppler images show the asteroid to be 3.5 ± 0.4 km in diameter and spheroidal; our corresponding nominal estimates of its visual and radar albedos are 0.07 and 0.24, respectively. Our IRTF spectrum shows the asteroid to be C-class with no evidence of hydration. Thermal models from the IRTF data provide a size and visual albedo consistent with the radar-derived estimate. We estimate the spin-pole to be within a few tens of degrees of λ = 317 °, β = - 20 °. Our radar observations reveal a secondary approximately 0.3 km in diameter, giving this binary one of the largest size differentials of any known NEA. The secondary is in a near-circular orbit with period 15.6 ± 0.1 h and a semi-major axis of 4.7 ± 0.2 km. Estimates of the binary orbital pole and secondary rotation rate are consistent with the secondary being in a spin-locked equatorial orbit. The orbit corresponds to a primary mass of M = 1.95 ± 0.25 × 1013 kg, leading to a primary bulk density of ρ = 0.9 + 0.5 / - 0.4 g cm-3, one of the lowest values yet measured for a main-belt or near-Earth asteroid.",
keywords = "Asteroids, composition, Radar observations, surfaces",
author = "Shepard, \{Michael K.\} and Margot, \{Jean Luc\} and Christopher Magri and Nolan, \{Michael C.\} and Joshua Schlieder and Benjamin Estes and Bus, \{Schelte J.\} and Volquardsen, \{Eric L.\} and Rivkin, \{Andrew S.\} and Benner, \{Lance A.M.\} and Giorgini, \{Jon D.\} and Ostro, \{Steven J.\} and Busch, \{Michael W.\}",
note = "Funding Information: We thank Ted Bowell and Alan Harris (DLR) for their reviews. We thank W. Bottke for locating probable source regions and for helpful discussions and H. Levison for a preprint of his paper. This work was supported by a Bloomsburg University Research and Disciplinary Grant to M.K.S. Student travel for J.S. was supported by Arecibo Observatory. The Arecibo Observatory is part of the National Astronomy and Ionosphere Center, which is operated by Cornell University under a cooperative agreement with the National Science Foundation. Some of this work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This material is based in part upon work supported by the National Aeronautics and Space Administration (NASA) under the Science Mission Directorate Research and Analysis Programs. Part of the data utilized in this publication were obtained and made available by the MIT-UH-IRTF Joint Campaign for NEO Reconnaissance. The IRTF is operated by the University of Hawaii under Cooperative Agreement No. NCC 5-538 with the National Aeronautics and Space Administration, Office of Space Science, Planetary Astronomy Program.",
year = "2006",
month = sep,
doi = "10.1016/j.icarus.2006.04.019",
language = "English (US)",
volume = "184",
pages = "198--210",
journal = "Icarus",
issn = "0019-1035",
publisher = "Academic Press Inc.",
number = "1",
}