Exo-planet detection with the COROT space mission. I. A multi-transit detection criterion

We present a detection criterion for exo-planets to be used with the space mission COROT. This criterion is based on the transit method, which suggests the observation of star dimming caused by partial occulations by planetary companions. When at least three transits are observed, we show that a cross-correlation technique can yield a detection threshold, thus enabling the evaluation of the number of possible detections, assuming a model for the stellar population in the Galaxy.