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New telescope puts Stanford sky gazers in the big leagues

Stanford astronomers are finally getting a large telescope that they can call their own.

The Hobby-Eberly Telescope, one of the world's largest and most powerful optical telescopes, is being dedicated this morning by the consortium of U.S. and German universities that built it.

The new telescope, which is located at the University of Texas' McDonald Observatory in Fort Davis, has several innnovative features. It has been designed specifically to obtain the spectra of stars and other celestial objects. Spectra are measurements of the brightness of light at different wavelengths, or colors, and they provide astronomers with considerably more information than ordinary, white-light images. By specializing the telescope in this fashion, its designers reduced the new telescope's cost to less than one-fifth that of other, comparable instruments. In addition, astronomers will not need to go to the telescope to make their observations. A new, more efficient way of scheduling the telescope's operations makes that impossible. Instead, data will be sent to them.

hetinterior.jpg Photo courtesy of Tom Sebring, McDonald Observatory

The honeycomb surface at the bottom of this interior view of the new Hobby-Eberly Telescope is the 33-foot primary mirror, which is made of 91 small, individually controlled mirror segments. The interior truss work supports the tracker, a system of small mirrors that move to keep the telescope focused on individual stars and other celestial objects as they move across the night sky.

Representatives from the five participating universities ­ the University of Texas-Austin, Pennsylvania State University, Stanford University, Ludwig-Maximilian University in Munich and Georg-August University in Göttingen ­ were expected to be on hand for today's dedication.

Stanford representatives planning to attend include physics department chair Blas Cabrera; physics professors Vahe Petrosian, Roger Romani and Robert Wagoner; and Hans Andersen, associate dean of the School of Humanities and Sciences and professor of chemistry. Although President Casper was unable to attend, his assistant, Jacqueline Wender, is scheduled to deliver the following statement from him:

"Stanford is very pleased to be involved in the Hobby-Eberly Telescope (HET) project. We look forward to the scientific developments that will be made possible once the full complement of spectroscopy instruments are operational. We anticipate that this facility will provide a focus for important collaborations among members of this international partnership.

"Stanford will continue to support its operation for at least the next 10 years, and we expect to contribute innovative new instrument designs through our research programs. In turn, the HET will provide to our faculty and students unparalleled opportunities in research and research training."


Exterior view of the Hobby-Eberly Telescope

The spectroscopy instruments to which Casper refers touch on a unique aspect of the Hobby-Eberly Telescope's design. It is specifically constructed to collect and analyze starlight, using a technique called spectroscopy. Spectroscopy tells astronomers considerably more about distant stars than plain, white-light images, including what the star is made of, how far away it is and how fast it is moving. Astronomers will use this capability to search for planets in orbit around other stars, learn more about the "dark matter" that surrounds galaxies, and refine theories about how stars are born and how they die.

Stanford's share of the project is 10 percent. That translates to about 25 observing nights a year, which will be divided among the eight active members of the astronomy program, who come from the physics, applied physics and electrical engineering departments. When Stanford bought into the project, the physics department also approved two new positions for scientists whose research will involve the telescope. One of those positions was filled two years ago by Assistant Professor Jeffrey A. Willick. A search is under way to fill the second billet.

The telescope appears to be a real bargain. Its construction cost totaled about $13.5 million, compared to the $100 million price tag for the comparably sized Keck Telescope constructed recently in Hawaii.

The bargain-basement price is due in large part to the fact that the telescope was designed for spectroscopy. This specific focus allowed experts at Pennsylvania State University to incorporate innovative design features to keep costs down. For example, considerable savings were realized by keeping the telescope's 33-foot primary mirror stationary rather than making it rigid enough so that it can move without flexing. The Hobby-Eberly Telescope is also the first optical telescope that will use a system of smaller mirrors as a moveable "tracker" to point the telescope, instead of moving the entire instrument, including the primary mirror. And the primary mirror, which is made up of 91 individually computer-guided mirrors, was able to be ground to a simpler, spherical curvature rather than the complex, parabolic geometry typical of most large telescope mirrors.

Befitting its radical design, the new telescope will not be managed in a conventional manner either. At most large telescopes, researchers submit a request to make a set of observations and, if it is granted, they are assigned to use the telescope for a given set of nights. If the weather is bad, or there are other problems, they are simply out of luck and must submit another request for the next viewing cycle.

The Hobby Eberly Telescope instead will use an approach called queue scheduling, a technique used for the Hubble Space Telescope. When viewing requests are received, they are assigned a priority by the committee of scientists running the telescope. Then, for any given period of observing time, the on-site staff will point the telescope at the highest-rated astronomical objects available to them. Thus, astronomers with high-priority observing projects will have multiple chances for successful observing. The approach allows the telescope to be used in the most efficient manner possible.

The new telescope will have another operational resemblance to the Hubble as well. Stanford scientists, and their colleagues from around the world, will not have to travel to the telescope to direct its operation and collect their data. Instead, their data will be sent to them on computer media. This will be a change from the traditional arrangement, but it will make it much easier, less expensive and more efficient to use the telescope, and it will increase the chances of successful observations.


Note: For more information about the Hobby-Eberly Telescope on the world wide web, go to

By David F. Salisbury

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