b'12 Carnegie Science|Summer 2019Astronomer Henrietta Swope (left, in front) gifted the funds for the 40-inch HenriettaThe 100-inch Irne du Pont telescope began construction in 1974. It was dedicated in Swope telescope at Las Campanas Observatory, which became operational in 1971.1976, with festivities for trustees and guests (right). It has been an astronomical The Swope telescope (middle) is shown under construction.workhorse since 1977. Today it is home to instruments including the Carnegie Images courtesy the Carnegie Observatories Astrometric Planet Search Camera, which was designed to hunt for planets using a different method from the Planet Finder Spectrograph and has also advanced our understanding of brown dwarfs and low-mass stars.Images courtesy the Carnegie ObservatoriesFifty Years at Las CampanasThe idea to build an observatory in the Southern Hemispheretelescopes at Las Campanas have allowed Carnegie researchers was older than Mount Wilson Observatory itself. In 1902,from the Observatories and the Department of Terrestrial Carnegies Advisory Committee on Astronomy argued for aMagnetism to make breakthrough discoveries in astronomy, southern observatory. At the time only half the sky, that seenastrophysics, and planetary science. Many of these milestones are from the Northern Hemisphere, was accessible to astronomy.enabled by Carnegies ongoing commitment to developing In the early 1960s there was still no place to see the centerinstrumentation, which can keep older telescopes relevant and of the Milky Way or the Magellanic Clouds. Horace Babcock,allow newer telescopes to do cutting-edge work.director of the Mount Wilson and Palomar Observatories, arguedThe Associated Universities for Research in Astronomy that building a southern observatory was vital.offered to sell the institution a small tract of land about 50 miles Babcock eventually earned the support of the institutionseast of La Serena. But in 1968, the Carnegie astronomers chose the trustees and president, Caryl Haskins, who supported four yearslarger Las Campanas site because of its remoteness, its seeing, and of site testing in Chile, Australia, and New Zealand. Chile offeredspace for future expansion. Eight thousand feet (2,400 meters) the best sites with the darkest skies and with the driest andabove sea level and 62 miles (100 kilometers) from La Serena, most stable air, a phenomenon called seeing.where the observatorys main office is located, Las Campanas was With ink-dark skies and the driest desert in the world,far from city lights, but still accessible. Chiles Atacama Desert boasts the best seeing in the world. It isBabcock negotiated directly with the president of Chile to now home to over 20 observatories. When Carnegie astronomerspurchase the 50,000 acres. In 1969, he signed a cooperative chose to build there 50 years ago, the southern migration ofagreement with the University of Chile under the auspices of the astronomers was just beginning. Over the decades, theChilean Ministry of Foreign Affairs. In the early 1990s, planning began for two 21.25-feet (6.5-meter) telescopes, the twin Magellans. The Magellan main mirrors are a radical departure from the solid-glass mirrors of the past. Each is made with borosilicate glass within a lightweight honeycomb structure. The image at left shows the first Magellan telescope under construction in 1996. In 2000, the first mirror was shipped from the University of Arizona Mirror Lab to Las Campanas, where it was installed. Inside the dome is shown at right. Bottom, the twin Magellan telescopes, the Baade and Clay are shown in panorama with the Milky Way. Images courtesy Carnegie Observatories, the GMTO,and Yuri Beletsky'