# International Consortium Is Created to Build World's Largest Submillimeter Telescope

PASADENA, Calif.—Five institutions from North America and Europe have created a consortium to oversee the building of a 25-meter submillimeter telescope on a high elevation in Chile. When completed in 2013, the $100 million instrument will be the premier telescope of its kind in the world. The project is formally known as the Cornell Caltech Atacama Telescope (CCAT), and has been in the works since a$2 million feasibility/concept design study was begun in 2004 by the California Institute of Technology and Cornell University. Now that the study has been completed, the partners are moving to the next phase of the process.

The consortium members are the California Institute of Technology and its Jet Propulsion Laboratory (JPL), Cornell University, the University of Colorado at Boulder, the University of British Columbia, and the United Kingdom Astronomy Technology Centre, which is part of the Science and Technology Facilities Council.

According to deputy project manager Simon Radford, who is based on the Caltech campus, the telescope will employ recent advances in technology that will provide unprecedented views of astronomical phenomena that cannot be studied at other wavelengths.

Because submillimeter-wavelength astronomy is especially effective for imaging phenomena that do not emit much visible light, the Atacama telescope will allow observations of stars and planets forming from swirling disks of gas and dust, will make measurements to determine the composition of the molecular clouds from which the stars are born, and could even discover large numbers of galaxies undergoing huge bursts of star formation in the very distant universe.

Also, the 25-meter telescope could be used to study the origin of large-scale structure in the universe.

The Atacama telescope will be located at an 18,400-foot altitude atop Cerro Chajnantor in Chile's Atacama Desert. The high altitude and dry conditions are important for submillimeter research, which is hampered by moisture in the air.

Of the projected $100 million cost,$20 million will go to state-of-the-art instrumentation. In particular, large submillimeter cameras will complement the huge size of the dish, which, at 25 meters, will have more than twice the area of the largest submillimeter telescope currently in existence.

The new cameras are made possible by recent developments in sensitive superconducting detectors, an area in which Caltech physics professor Jonas Zmuidzinas and his colleagues have been making important contributions. The new wide-field cameras will produce very sensitive panoramic images of the submillimeter sky.

Scientists from Caltech and JPL who will be involved in the project include Andrew Blain, Geoff Blake, Paul Goldsmith, Sunil Golwala, Andrew Lange, Tom Phillips, Anthony Readhead, Anneila Sargent, Eugene Serabyn, Tom Soifer, and Michael Werner, among others. The director of CCAT is Riccardo Giovanelli of Cornell, and the project manager is Thomas Sebring, also based at Cornell.

The 25-meter telescope is a natural progression in Caltech and JPL's long-standing interest in submillimeter and infrared astronomy, which started in the 1960s with the first infrared sky survey, carried out by professors Robert Leighton and Gerry Neugebauer on Mount Wilson.

In 1983, under Neugebauer's leadership, JPL launched the Infrared Astronomical Satellite, or IRAS, which discovered huge numbers of infrared-bright objects. This success paved the way to JPL's current infrared mission, the Spitzer Space Telescope. Meanwhile, Leighton went on to design a 10.4-meter submillimeter telescope, which by 1987 led to the construction and operation of the Caltech Submillimeter Observatory (CSO) on Mauna Kea, Hawaii. The CSO is funded by the National Science Foundation, and Tom Phillips, a professor of physics at Caltech, serves as director.

The CSO is fitted with sensitive submillimeter detectors and cameras, making it ideal for seeking out and observing the diffuse gases and their constituent molecules, crucial to understanding star formation. This experience served as the foundation for JPL's participation in the European Space Agency's Herschel Space Observatory.

The advantages of the new telescope, in addition to technological advances in instrumentation and the dry sky of the Atacama region, will also include a larger and more accurate mirror. The 25-meter telescope should provide six to 12 times the light-gathering ability of the CSO, depending on the exact wavelength. Also, the larger diameter and better surface will result in much sharper images of the sky.

The CCAT is designed to emphasize wide-field surveys of the submillimeter sky that will guide follow-up observations with telescope arrays such as the Combined Array for Research in Millimeter-wave Astronomy (CARMA), which Caltech played a leading role in developing, and the international Atacama Large Millimeter Array (ALMA), also located in northern Chile.

"CCAT will be a particularly important complement to ALMA," said Caltech astronomy professor Anneila Sargent, director of CARMA and chair of the interim CCAT board. "CCAT will enable consortium scientists to make optimal use of ALMA's submillimeter capabilities to address fundamental questions about star and galaxy formation."

A great opportunity therefore exists for submillimeter astronomy. In fact, an independent blue-ribbon panel chaired by Robert W. Wilson, 1978 Nobel Laureate who earned his doctorate in physics at Caltech, recently reported that the Atacama project "will revolutionize astronomy in the submillimeter/far infrared band and enable significant progress in unraveling the cosmic origin of stars, planets, and galaxies.

"CCAT is very timely and cannot wait," the panel said.

"It is a very exciting time for submillimeter astronomy," Zmuidzinas said when the 2004 feasibility study began. "We are making rapid progress on all fronts-in detectors, instruments, and new facilities-and this is leading to important scientific discoveries."