^BCerro Tololo observatory.^b Telescope domes at the Cerro Tololo Inter-American Observatory (CTIO) near La Serena, Chile. The domes are (from left to right): the Yale 1 metre telescope; Curtis- Schmidt telescope; 4 metre Victor Blanco telescope; 1.5 metre Ritchey-Chretien telescope; and 0.9 metre telescope. The high altitude of Cerro Tololo (2200 metres), & the clear air above it, are ideal for the observatory because atmospheric distortions to incoming light are reduced. In 1997 Cerro Tololo is operated by the National Optical Astronomy Observatories (NOAO).