The Monitor project: the search for transits in the open cluster NGC 2362

We present the results of a systematic search for transiting planets in a similar to 5 Myr open cluster, NGC 2362. We observed similar to 1200 candidate cluster members, of which similar to 475 are believed to be genuine cluster members, for a total of similar to 100 h. We identify 15 light curves with reductions in flux that pass all our detection criteria, and six of the candidates have occultation depths compatible with a planetary companion. The variability in these six light curves would require very large planets to reproduce the observed transit depth. If we assume that none of our candidates are, in fact, planets then we can place upper limits on the fraction of stars with hot Jupiters (HJs) in NGC 2362. We obtain 99 per cent confidence upper limits of 0.22 and 0.70 on the fraction of stars with HJs (f(p)) for 1-3 and 3-10 d orbits, respectively, assuming all HJs have a planetary radius of 1.5R(Jup). These upper limits represent observational constraints on the number of stars with HJs at an age less than or similar to 10 Myr, when the vast majority of stars are thought to have lost their protoplanetary discs. Finally, we extend our results to the entire Monitor project, a survey searching young, open clusters for planetary transits, and find that the survey as currently designed should be capable of placing upper limits on f(p) near the observed values of f(p) in the solar neighbourhood.