The transit light curve project. I. Four consecutive transits of the exoplanet XO-1b

Matthew J. Holman, Joshua N. Winn, David W. Latham, Francis T. O'Donovan, David Charbonneau, Gáspár A. Bakos, Gilbert A. Esquerdo, Carl Hergenrother, Mark E. Everett, P. Á L. András

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167 Scopus citations


We present RIz photometry of four consecutive transits of the newly discovered exoplanet XO-1b. We improve on the estimates of the transit parameters, finding the planetary radius to be RP = 1.184 -0.018+0.028 RJ, and the stellar radius to be R* = 0.928-0.013+0.018 R, assuming a stellar mass of M* = (1.00 ± 0.03) M⊙. The uncertainties in the planetary and stellar radii are dominated by the uncertainty in the stellar mass. These uncertainties increase by a factor of 2-3 if a more conservative uncertainty of 0.10 M is assumed for the stellar mass. Our estimate of the planetary radius is smaller than that reported by McCullough and coworkers, and the resulting estimate for the mean density of XO-1b is intermediate between that of the low-density planet HD 209458b and the higher density planets TrES-1 and HD 189733b. The timings of the transits have an accuracy ranging from 0.2 to 2.5 minutes and are marginally consistent with a uniform period.

Original languageEnglish (US)
Pages (from-to)1715-1723
Number of pages9
JournalAstrophysical Journal
Issue number2 I
StatePublished - Dec 1 2006
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Planetary systems
  • Stars: individual (GSC 02041-01657)
  • Techniques: photometric


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