The German-Spanish Astronomical Center at Calar Alto is located in the Sierra de Los Filabres (Andaluc?a, Southern Spain) north of Almeria. It is operated jointly by the Max-Planck-Institut f?r Astronomie (MPIA) in Heidelberg, Germany, and the Instituto de Astrof?sica de Andaluc?a (CSIC) in Granada/Spain. Calar Alto provides three telescopes with apertures of 1.23m, 2.2m and 3.5m to the general community. A 1.5m-telescope, also located on the mountain, is operated under the control of the Observatory of Madrid.