Keeping Their Eyes on the Skies
By Terry Devitt '78, MA'85

The answers to these questions and many more can be retrieved only with the help of telescopes like WIYN. As a newer, technologically advanced instrument, it has some notable advantages. At its heart is the 3.5-meter primary mirror. Created at the University of Arizona by legendary mirror maker Roger Angel, it was forged in a special rotating furnace, which forced molten glass into a deep parabolic shape, giving WIYN an extraordinarily wide field of view. The technique produces mirror blanks that are not only almost perfectly shaped, but that are far lighter than those of conventional manufacture. With this relatively light mirror — weighing in at 4,350 pounds — forged into a deeper parabola, the entire observatory can be smaller and more versatile, and the telescope itself becomes far less costly than comparable telescopes of conventional design.

The WIYN telescope, perched on an Arizona mountaintop.

WIYN, for example, is routinely compared to a 4-meter telescope on the other side of the mountain, which is housed in a 10-story dome and has a primary mirror that weighs nearly seven times that of WIYN. In fact, four telescopes the size of WIYN could nest comfortably within its massive walls, and the 4-meter telescope itself is longer than the 3-story WIYN Observatory is high. Yet WIYN's state-of-the-art mirror and its modern instrumentation give it a significant performance edge. Its thin, lightweight mirror is equipped with "active optics" — sixty-six small, computer-controlled actuators that continuously press the mirror into its optimal shape, effectively erasing the irregularities caused by temperature gradients and the movement of the telescope.

On a dark night, when the "seeing" is good, WIYN can zero in on objects that are 10 million times fainter than what can be seen with the unaided human eye. It can look back 14 billion light-years, nearly to the edge of our 15-billion-year-old universe. But at those great cosmological distances, the telescope is pushing the limits of its capabilities. Its realm of effectiveness as a scientific instrument is more in the 7-billion-year range and closer.

"We do more detailed studies of things nearby," says Pisano. "It's much easier to observe things at greater distances with a bigger telescope."

The relationship between the WIYN Observatory and UW-Madison astronomy is founded on a mandate to explore the universe. But it confers another commodity beyond understanding the subtleties of binary star systems, stellar nurseries, and galactic accidents: opportunities for UW-Madison students to get their hands on one of the best optical telescopes in the world. In a field in which only one in four graduate students lands a tenure-track job, direct access to a telescope, and perhaps even a night or two of your own observation time in any given year, is a distinct competitive advantage.

"It helps us attract superb graduate students," says Robert Mathieu, a UW-Madison professor of astronomy and president of the WIYN board of directors. "And it makes them better astronomers. Having our own telescope means they can do projects that they couldn't do otherwise."

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