The transit light curve (TLC) project. VI. Three transits of the exoplanet TrES-2

Of the nearby transiting exoplanets that are amenable to detailed study, TrES-2 is both the most massive and the one with the largest impact parameter. We present z-band photometry of three transits of TrES-2. We improve on the estimates of the planetary, stellar, and orbital parameters, in conjunction with the spectroscopic analysis of the host star by Sozzetti and coworkers. We find the planetary radius to be R-p = 1.222 +/- 0.038 R-Jup and the stellar radius to be R-star=1.003 +/- 0.027 R-circle dot. The quoted uncertainties include the systematic error due to the uncertainty in the stellar mass (M-star=0.980 +/- 0.062 M-circle dot). The timings of the transits have an accuracy of 25 s and are consistent with a uniform period, thus providing a baseline for future observations with the NASA Kepler satellite, whose field of view will include TrES-2.