An extrasolar planet transit search with Subaru Suprime-Cam

We report the results of a prototype photometric search for transiting extrasolar planets using Subaru Suprime-Cam. Out of about 100000 stars monitored around the Galactic plane (l = 90°, b = 0°), we find that 7700 show photometric precision better than 1% for 60 s exposures, which is required to detect extrasolar planets by the transit method. Thus, Suprime-Cam has the photometric stability and accuracy necessary for a transiting planet survey. During this observing run, we detected three objects (around 18.5 mag for i′-band) that exhibit a single full transit-like light curve with a fractional depth of < 5%. While a spectroscopic follow-up remains to be done using future telescopes in the 20-30 m class, the estimated parameters for the three systems are consistent with the planetary size companions around main-sequence stars. We also found two eclipsing binary candidates and eleven variable stars exhibiting W UMa-like light curves.