On the detection of satellites of extrasolar planets with the method of transits

We compute the detection probability of satellites of extrasolar planets wi th the method of transits, under the assumption that the duration of the ob servations is at least as long as the planet orbital period. We separate th e cases when the parent planet does and does not also transit over the star . The possible satellites are assumed to have orbital radii between the Roc he limit and the Hill radius. We find that if a satellite is extended enoug h to produce a detectable drop in the stellar lightcurve, the probability t o detect it when the planet also transits over the star is nearly unity. If the planet does not transit, the probability to detect a Jupiter-Iike or t errestrial satellite is modest, but it can be comparable to that of detecti ng a planet if the satellite orbital radius is large. If a satellite is not extended enough to produce a detectable drop in the stellar lightcurve dur ing a transit, it might still be detected through the time shift of planeta ry transits resulting from the rotation of the planet around the barycenter of the planet-satellite system.