Survey for Transiting Extrasolar Planets in Stellar Systems. III. A Limit on the Fraction of Stars with Planets in the Open Cluster NGC 1245

We analyze a 19 night photometric search for transiting extrasolar planets in the open cluster NGC 1245. An automated transit search algorithm with quantitative selection criteria finds six transit candidates; none are bona fide planetary transits. We characterize the survey detection probability via Monte Carlo injection and recovery of realistic limb-darkened transits. We use this to derive upper limits on the fraction of cluster members with close-in Jupiter radii, RJ, companions. The survey sample contains ~870 cluster members, and we calculate 95% confidence upper limits on the fraction of these stars with planets by assuming that the planets have an even logarithmic distribution in semimajor axis over the Hot Jupiter (HJ; 3.0 < P day-1 < 9.0) and Very Hot Jupiter (VHJ; 1.0 < P day-1 < 3.0) period ranges. For 1.5RJ companions we limit the fraction of cluster members with companions to