2008ApJ...674.1117W

We present the results of a deep, wide-field search for transiting hot Jupiter (HJ) planets in the globular cluster ω Centauri. As a result of a 25 night observing run with the ANU 40 inch (1 m) telescope at Siding Spring Observatory, a total of 109,726 stellar time series composed of 787 independent data points were produced with differential photometry in a 52'x52' (0.75 deg²) field centered on the cluster core, but extending well beyond. Taking into account the size of transit signals as a function of stellar radius, 45,406 stars have suitable photometric accuracy (≤0.045 mag to V=19.5) to search for transits. Of this sample, 31,000 stars are expected to be main-sequence cluster members. All stars, both cluster and foreground, were subjected to a rigorous search for transit signatures; none were found. Extensive Monte Carlo simulations based on our actual data set allow us to determine the sensitivity of our survey to planets with radii ∼1.5 R_Jup and thus place statistical upper limits on their occurrence frequency F. Smaller planets are undetectable in our data. At 95% confidence, the frequency of very hot Jupiters (VHJs) with periods P satisfying 1 day<P<3 days can be no more than F_VHJ<1/1040 in ω Cen. For HJs and VHJs distributed uniformly over the orbital period range 1 day<P<5 days, F_VHJ+HJ<1/600. Our limits on large, short-period planets are comparable to those recently reported for other Galactic fields, despite being derived with less telescope time.