Radar and infrared observations of binary near-Earth Asteroid 2002 CE26

Michael K. Shepard, Jean Luc Margot, Christopher Magri, Michael C. Nolan, Joshua Schlieder, Benjamin Estes, Schelte J. Bus, Eric L. Volquardsen, Andrew S. Rivkin, Lance A.M. Benner, Jon D. Giorgini, Steven J. Ostro, Michael W. Busch

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)198-210
Number of pages13
Issue number1
StatePublished - Sep 2006
Externally publishedYes


  • Asteroids
  • composition
  • Radar observations
  • surfaces

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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