Plans for the world's largest solar optical telescope moved forward Jan. 6 when the board of directors of the Association of Universities for Research in Astronomy (AURA), endorsed recommendations to build the 4-meter (13-ft) Advanced Technology Solar Telescope (ATST) at Haleakala, Maui, Hawaii.

An artist's drawing shows the ATST Observatory Facility. Source: NSO

ATST, an international project led by the National Science Foundation's National Solar Observatory (NSO), will become the world's most powerful solar optical telescope when it starts operating around 2012. AURA operates the NSO under a cooperative agreement with the NSF. Principal partners on ATST are the University of Hawaii, the University of Chicago, the New Jersey Institute of Technology, and the High Altitude Observatory. Haleakala is home to the University of Hawaii's Institute for Astronomy and the Mees Solar Observatory. Other partners include the National Aeronautics and Space Administration and the U.S. Air Force.

"The Advanced Technology Solar Telescope will be the world's premier observatory for studying the detailed processes that occur on the Sun," said Dr. William Smith, AURA's president. "It is therefore appropriate that we have chosen a premier site that will host this facility."

Dr. Rolf-Peter Kudritzki, director of the IfA, announced that the ATST project is moving forward to undertake a joint State/Federal Environmental Impact Statement at Haleakala, and that the ATST project is identified as a potential new facility in the University of Hawaii, Institute for Astronomy's Haleakala Observatory Long Range Development Plan.

Selection of Haleakala follows almost three years of studies that started with 70 potential sites. The final selection was then based on extensive surveys at six of the 70 sites and narrowed to three finalist sites: Haleakala, Big Bear Lake, CA and La Palma in the Canary Islands of Spain. The ATST Science Working Group recommended Haleakala as the prime candidate in October 2004. The NSO's Solar Observatory Council endorsed the recommendation in December and forwarded it to the AURA board.

"A range of seeing conditions, including those needed to study the faint corona, makes Haleakala an excellent site," said Dr. Stephen Keil, NSO's director and the ATST principal investigator. "The ATST site selection and the ATST design represent the work of a large segment of the U.S. and international solar communities. The major scientific goals of observing and understanding magnetic fields at their fundamental spatial and temporal scales at all heights in the solar atmosphere are best fulfilled on Haleakala."

By combining a large aperture with advances in adaptive optics to correct for atmospheric blurring, ATST will measure the structure and evolution of solar magnetic structures at much finer spatial and temporal scales than is possible with existing telescopes. Most important, ATST will be able to measure these structures both on the bright disk and in the faint corona, and from near ultraviolet through out to the relatively unexplored thermal infrared part of the spectrum.

Few astrophysical research disciplines are as directly relevant to life on Earth as understanding and perhaps predicting variations in solar activity. These variations impact humanity with events ranging from disrupted satellite communications to global changes in Earth's climate. ATST is the tool to measure the fine-scale magnetism that drives solar activity.