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ATST: A New Solar Telescope for a New Century

by Jeff Kuhn

A conceptual design of ATST. The final design has not yet been determined. Source:

IfA scientists are participating in a project to design and develop the next-generation solar research telescope called the Advanced Technology Solar Telescope (ATST). This instrument represents the largest single advance in ground-based solar observing since the time of Galileo! The project is being funded by the National Science Foundation (NSF).

Why We Need the ATST. Changes on the Sun directly affect the climate here on Earth. These can be small, short-term changes lasting but a few years, or they can be long-term changes over thousands of years. There is no doubt that in the past the Sun caused climate changes that make current trends in global warming look mild.

With technology that is now available, scientists do not understand, and cannot predict, what will happen on the Sun and how it will affect Earth, even over the next decade. The ATST will enable them to measure changes in the Sun's magnetic fields and determine how these changes affect the solar system environment between Earth and the Sun.

Project Participants. The effort to design and develop the ATST is centered at the National Solar Observatory (Tucson, Arizona) and Sacramento Peak Observatory (New Mexico). The co-investigator institutions for this activity are the University of Hawaii, the University of Chicago, the High Altitude Observatory in Boulder, and the Big Bear Solar Observatory (of the New Jersey Institute of Technology). At IfA, solar scientists Jeff Kuhn (lead), Haosheng Lin, and Donald Mickey, and instrument scientist Roy Coulter are working on this effort.

A total of 22 institutions are participating in the design and development phase of the project in some way. Toward the end of 2004, this phase will culminate in the presentation to NSF of a detailed plan for locating and building the ATST facility.

What will the ATST look like? The ATST telescope will be, by far, the largest solar telescope ever built. With a primary mirror diameter of 4 meters (13 feet) and a unique off-axis telescope design, it will have enough resolution and collect enough solar radiation to allow scientists to see and measure the magnetic structures within the solar atmosphere.

The telescope design is unusual in that the light does not pass by or near to the secondary mirror in its path to the primary. A small prototype version of the ATST telescope called SOLARC (Scatter Free Observatory for Limb Active Regions and Coronae) is already operating on the summit of Haleakala. This NASA-funded instrument has been useful both for advancing solar coronal research in its own right and as a working facility for testing ATST design and engineering concepts.

This image shows one of the first observations from SOLARC revealing the complicated structure of a sunspot when it is seen with the superb resolution possible from Haleakala.

Where will the ATST be built? Many who have studied the possible locations for this telescope believe that there is no better place in the world for it than the summit of Haleakala. If built there, it will have the greatest scientific impact. With care and proper planning, this can be accomplished without negative environmental or cultural impacts on the mountain summit. IfA scientists are now collecting and monitoring atmospheric conditions on Haleakala in preparation for the ATST siting decision.

As a national scientific institution, the ATST project will benefit from the scientific and technical infrastructure that the Institute for Astronomy, the University of Hawaii, and the state of Hawaii can provide. In return, the state will benefit because ATST will bring an influx of federal funds, high-paying jobs, and educational opportunities, and will raise the state's profile as a place where successful scientific and high-technology projects occur. While the design is not finalized, it is likely that the ATST will be a $100 million facility.

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