Direct measurement of the size of 2003 UB313 from the bubble space telescope

M. E. Brown, E. L. Schaller, H. G. Roe, D. L. Rabinowitz, C. A. Trujillo

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


We have used the Hubble Space Telescope to directly measure the angular size of the large Kuiper Belt object 2003 UB313. By carefully calibrating the point-spread function of a nearby field star, we measure the size of 2003 UB313 to be 34.3 ± 1.4 mas, corresponding to a diameter of 2400 ± 100 km or a size ∼5% larger than Pluto. The V-band geometric albedo of 2003 UB313 is 86% ± 7%. The extremely high albedo is consistent with the frosty methane spectrum, the lack of red coloring, and the lack of observed photometric variation on the surface of 2003 UB313. Methane photolysis should quickly darken the surface of 2003 UB313, but continuous evaporation and redeposition of surface ices appears capable of maintaining the extreme albedo of this body.

Original languageEnglish (US)
Pages (from-to)L61-L63
JournalAstrophysical Journal
Issue number1 II
StatePublished - May 29 2006
Externally publishedYes


  • Comets: General
  • Infrared: Solar system
  • Minor planets, asteroids

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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