Therefore, in December 2011 and January 2012, CoRoT was part of a large international observing campaign involving four space telescopes and several ground-based observatories. All instruments observed about 4000 stars in the young cluster NGC 2264 simultaneously for about one month at different wavelengths. The Canadian space mission MOST targeted the brightest stars in the cluster in the optical light, while CoRoT observed the fainter members. MOST and CoRoT observed NGC 2264 continuously for 39 days. The NASA satellites Spitzer and Chandra measured at the same time the stars in the infrared (for 30 days) and the X-ray domains (for 300 kiloseconds). Ground-based observations were taken also at the same time, for example, with the ESO Very Large Telescope in Chile, the Canadian-French-Hawaiian Telescope in Hawaii, the McDonald Observatory in Texas, or the Calar Alto Observatory in Spain.