The search for distant objects in the solar system using spacewatch

Jeffrey A. Larsen, Eric S. Roe, C. Elise Albert, Anne S. Descour, Robert S. McMillan, Arianna E. Gleason, Robert Jedicke, Miwa Block, Terrence H. Bressi, Kim C. Cochran, Tom Gehrels, Joseph L. Montani, Marcus L. Perry, Michael T. Read, James V. Scotti, Andrew F. Tubbiolo

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


We have completed a low-inclination ecliptic survey for distant and slow-moving bright objects in the outer solar system. This survey used data taken over 34 months by the University of Arizona's Spacewatch Project based at Steward Observatory, Kitt Peak. Spacewatch revisits the same sky area every three to seven nights in order to track cohorts of main-belt asteroids. This survey used a multiple-night detection scheme to extend our rate sensitivity to as low as 0.012 arcsec hr-1. When combined with our plate scale and flux sensitivity ( V ≈ 21 ), this survey was sensitive to Mars-sized objects out to 300 AU and Jupiter-sized planets out to 1200 AU. The survey covered approximately 8000 deg2 of raw sky, mostly within 10° of the ecliptic but away from the Galactic center. An automated motion-detection program was modified for this multinight search and processed approximately 2 terabytes of imagery into motion candidates. This survey discovered 2003 MW 12, currently the tenth largest classical Kuiper Belt object. In addition, several known large Kuiper Belt objects and Centaurs were detected, and the detections were used with a model of our observational biases to make population estimates as a check on our survey efficiency. We found no large objects at low inclinations despite having sufficient sensitivity in both flux and rate to see them out as far as 1200 AU. For low inclinations, we can rule out more than one to two Pluto-sized objects out to 100 AU and one to two Mars-sized objects to 200 AU.

Original languageEnglish (US)
Pages (from-to)1247-1270
Number of pages24
JournalAstronomical Journal
Issue number4
StatePublished - Apr 2007


  • Kuiper belt
  • Minor planets, asteroids
  • Solar system: formation
  • Surveys

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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