This is the light-curve of the parent star of COROT-exo-2b.

The observation was carried out for 140 days. The light-curve contains 78 passages of the planet in front of the star. This is a record, compared to previous (ground-based) observations where transits sometimes take place in the daytime and are impossible to observe.

The photometric precision obtained in this light-curve is also without precedence, and remains constant during the whole sequence. It reaches 160 parts per million in an integration time of 2.5 minutes – a value impossible to obtain with any ground-based instrument. The light-curve also contains much information about the star itself. It shows periodic modulations, probably the result of different rotational velocities at different latitudes of the star.

This is another nice example of COROT’s superior performance and demonstrates the impact that this mission will have on our understanding of stellar activity and its connection to extrasolar planets.