Summer 2000 -- Vol. 17, No. 1

First Results Reported as Hobby-Eberly Telescope Enters Early Operations Phase

The Hobby-Eberly Telescope, a joint venture by Penn State and four other universities, has begun regular scientific use in its early-operations phase after a highly successful initial-testing phase.

"The early-operations phase marks the beginning of regular use of the telescope for science," said Frank Bash, chairman of the Hobby-Eberly Telescope Board. "This is an important milestone for this unique and powerful new scientific instrument, and we want the astronomical community to know about it."

Scientists at all institutions participating in the telescope have been eagerly anticipating the flow of astronomical data that early operations are now producing.

Photo: L. Ramsey, Penn State

"The telescope is already paying scientific dividends by making contributions in the areas for which it was designed: spectroscopic surveys and time-domain astrophysics," said Larry Ramsey, the Project Scientist for the telescope and professor of astronomy and astrophysics at Penn State. Ramsey is one of the original inventors of the telescope, along with Daniel Weedman, formerly at Penn State and now at the National Science Foundation Division of Astronomical Science.

The telescope contains the worldšs largest primary mirror, measuring 11 meters (433 inches) from edge to edge. Because of the way the Hobby-Eberly Telescope will be used, 9.2 meters (362 inches) of its surface will be accessible at any given time. Thus, the Hobby-Eberly Telescope is effectively the third-largest telescope in the world, after the twin 10-meter (393-inch) Keck I and Keck II telescopes in Hawaii.

So far, users of the telescope report exciting results. The first paper based on observations with the telescope was recently accepted by the Publications of the Astronomical Society of the Pacific. Donald Schneider, professor of astronomy and astrophysics at Penn State; Gary Hill, of the University of Texas; and Xiaohui Fan, a graduate student at Princeton University, have led a project to obtain spectra of high-redshift quasar candidates found by the Sloan Digital Sky Survey. They discovered five quasars with redshifts between 2.9 and 4.2. As their work continued, the telescope has observed more than a dozen distant quasar candidates.

Quasars are the most luminous class of objects in the universe. One of the quasars discovered by the telescope is so far away that the light we see from it began traveling toward Earth when the universe was only one-eighth of its current age.

Penn State is leading the effort to develop the software required to calibrate the data and had a small role in constructing the spectrograph used for the telescope observation. Penn State assistant professor Michael Eracleous is overseeing the data-processing effort. His team consists of a number of Penn State faculty and students.

The telescope attained "first light" in December 1996 and "first spectrum" in September 1997. It was dedicated in October 1997. The telescopešs commissioning phase, during which the telescopešs sophisticated optical, mechanical, and electrical systems were debugged, integrated, and optimized for science operations, lasted until October 1999. In early operations, the telescope will be used for scientific research for half of each month. So far, the telescope is operating with the Marcario Low-Resolution Spectrograph, designed and built by a team led by Gary Hill and Phillip MacQueen of McDonald Observatory, and the Upgraded Fiber Optic Echelle spectrograph, an instrument built at Penn State by Ramsey and Penn State graduate students Jason Harlow and David Andersen.

A high-resolution spectrograph, designed and built by a team led by Robert Tull of McDonald Observatory, will be installed in mid-2000, to be followed by a medium-resolution spectrograph, being constructed under the direction of Ramsey.

Edward L. Robinson, the William B. Blakemore II Regents Professor in Astronomy at the University of Texas at Austin, has used the telescope to observe a new X-ray star in visible light. The X-ray properties of the new star, named J1859+226, show that it is probably a black hole that has begun to swallow gas pulled off a normal star orbiting around the black hole.

New X-ray stars, called X-ray transients, are rare. About one X-ray transient erupts per year in our galaxy. J1859+226 erupted a week after the beginning of Early Operations on the telescope. Because objects observed with the telescope are chosen dynamically and in real time (the telescope is "queue scheduled"), Robinson was able to begin observing J1859+226 as soon as it was identified at visible wavelengths, several days before the peak of the eruption. He continued observing J1859+226 every one or two days for the next six weeks. The telescope observations are a unique contribution to understanding how black holes attract and swallow matter.

The namesakes of the Hobby-Eberly Telescope are William P. Hobby, the former Lieutenant Governor of Texas, and Robert E. Eberly of Pennsylvania, an industrialist and philanthropist.

The telescope stands on Mount Fowlkes at McDonald Observatory in west Texas, which has the darkest skies of any major observatory in the continental United States.

Joel Barna

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