Radar and photometric observations and shape modeling of contact binary near-Earth Asteroid (8567) 1996 HW1

Christopher Magri, Ellen S. Howell, Michael C. Nolan, Patrick A. Taylor, Yanga R. Fernández, Michael Mueller, Ronald J. Vervack, Lance A.M. Benner, Jon D. Giorgini, Steven J. Ostro, Daniel J. Scheeres, Michael D. Hicks, Heath Rhoades, James M. Somers, Ninel M. Gaftonyuk, Vladimir V. Kouprianov, Yurij N. Krugly, Igor E. Molotov, Michael W. Busch, Jean Luc MargotVladimir Benishek, Vojislava Protitch-Benishek, Adrian Galád, David Higgins, Peter Kušnirák, Donald P. Pray

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


We observed near-Earth Asteroid (8567) 1996 HW1 at the Arecibo Observatory on six dates in September 2008, obtaining radar images and spectra. By combining these data with an extensive set of new lightcurves taken during 2008-2009 and with previously published lightcurves from 2005, we were able to reconstruct the object's shape and spin state. 1996 HW1 is an elongated, bifurcated object with maximum diameters of 3.8 × 1.6 × 1.5. km and a contact-binary shape. It is the most bifurcated near-Earth asteroid yet studied and one of the most elongated as well. The sidereal rotation period is 8.76243 ± 0.00004. h and the pole direction is within 5° of ecliptic longitude and latitude (281°, -31°). Radar astrometry has reduced the orbital element uncertainties by 27% relative to the a priori orbit solution that was based on a half-century of optical data. Simple dynamical arguments are used to demonstrate that this asteroid could have originated as a binary system that tidally decayed and merged.

Original languageEnglish (US)
Pages (from-to)210-227
Number of pages18
Issue number1
StatePublished - Jul 2011
Externally publishedYes


  • Asteroids
  • Photometry
  • Radar observations

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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