Since 2005, a group at IFAE, alongside a group at ICE (Institut de Ciències de l’Espai) and another at CIEMAT (Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas) in Madrid, collaborates in the Dark Energy Survey (DES) international project, led by Fermilab (USA). The main goal of the project is to survey 5000 deg2 of the southern galactic sky, measuring positions on the sky, shapes and redshifts of about 300 million galaxies and 15000 galaxy clusters. Furthermore, another 10 deg2 of the sky will be repeatedly monitored with the goal of measuring magnitudes and redshifts of over 1000 distant type-Ia SNe. These measurements will allow detailed studies of the properties of the so-called “dark energy” that drives the current accelerated expansion of the universe.
To perform the survey, the DES Collaboration is building a large wide-field CCD camera (DECam) that will give images covering 3 deg2 on the sky. The camera, shown in Figure 1, will be mounted at the prime focus of the 4-meter Blanco Telescope, located in Cerro Tololo in Chile. In return, DES is granted 30% of all the observation time for 5 years (2011-2015).