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April 27, 2000

Observatory director hopes to be working with, not competing against, space satellites

As satellite telescopes supersede ground-based astronomy, Pitt's Allegheny Observatory has largely been eclipsed as a center of basic research.

The North Side landmark's federal grants dried up two years ago. Last month, the observatory laid off its chief technician, Tim Persinger. Chief observer Tom Reiland will be let go at the end of June.

But except for mourning the loss of "two of the best people I've ever worked with," Allegheny Observatory director George D. Gatewood sounds upbeat about the 87-year-old facility.

"To tell you the truth, I think we've been unusually fortunate in that we've survived this long as an East Coast observatory, when virtually every other one has closed down," Gatewood said. "Even the larger, ground-based telescopes on mountain tops are beginning to see the end of their time. We're really in the space age now.

"And whereas, in the past, we tried to compete with the satellites, our new direction is to work with them."

Allegheny Observatory computers, together with computers at the U.S. Naval Observatory in Washington, D.C., and the Smithsonian Observatory in Cambridge, Mass., will crunch data received from the Full-Sky Astrometric Mapping Explorer (FAME) space telescope that NASA plans to launch in 2004.

Gatewood said FAME is expected to measure activity around some 40 million stars "instead of the few hundred stars that we've been able to cover." And FAME's observations are likely to be 20 times more precise than images produced by the Allegheny Observatory's legendary Thaw 30-inch photographic refractor, he said.

Allegheny also will apply to participate in another NASA space telescope project planned for later in the decade: the Space Interferometer Mission (SIM), aimed at detecting additional planets. (Of the 32 known planets outside our solar system, two — located in the Ursa Major system, eight light years away — were foundby Gatewood, in collaboration chief observer Reiland.) Allegheny's NASA funding could total as much as $170,000 annually by the end of the decade if the observatory's SIM and other funding applications are approved, according to Gatewood.

Frank Tabakin, chairperson of Pitt's physics and astronomy department, said he's "guardedly optimistic" about the observa-tory's funding prospects.

"There have been many cases in this department where research groups have temporarily lost their funding, and then came back very strong a year or two later," he said. "If, every time a group lost its grant we closed up shop, we'd be in pretty bad shape. We would have closed some major, successful components of our department." Tabakin declined to specify those groups. "I don't want to name names because they're not particularly proud of having that interlude," he said, with a laugh.

Tabakin and Gatewood voiced concern about an April 23 Pittsburgh Post-Gazette report on Allegheny's decline as a ground-based observatory. It wasn't the story that bothered them, but the headline: "Allegheny Observatory put out to pasture."

"That's the kind of thing that can create a certain hysteria and do damage by discouraging contributors" to the endowments that support the observatory, Tabakin said.

Academic programs in Pitt's physics and astronomy department shouldn't suffer as a result of the loss of research funding and resulting layoffs at the Allegheny Observatory, according to Tabakin. "As long as we still have some access to the observatory, [cutbacks] shouldn't make any difference to our students or faculty," he said.

"Relatively few of our students go into astronomy. The great majority are in physics and astrophysics," Tabakin noted. "Of the 500 to 600 Ph.D. students we've had in our department over the last 80 years, only about 2 or 3 percent have been in astronomy. Right now, we don't have any" astronomy Ph.D. students, Tabakin said.

Undergraduate astronomy majors can get all the celestial observation experience they need with smaller telescopes provided by the department, he added.

q Observatory director Gatewood said the facility plans to be more aggressive and creative in applying for research grants to measure its photographic plates charting star positions since 1915.

"In our plate vault, there are about 500,000 exposures of the sky, taken with a precision equal to anything that any photographic telescope has ever achieved," Gatewood said. "Only about one-third of those plates have been measured. The rest are just sitting here in our basement."

Evidence of heretofore unknown planets could be among those plates, Gatewood said.

By its gravitational pull, a planet orbiting a star will cause that star to "wobble" slightly in its own orbit. By scientifically measuring microscopic wobbles in the movements of distant stars over years, astronomers can detect new planets. That's how the two Ursa Major planets were found, Gatewood pointed out.

"We've gone to the [federal funding] agencies on several occasions and asked them for money to hire plate measurers," he said. "The problem is, the agencies don't see that as being very futuristic. It's difficult for somebody who has their eye on the future to realize the significance of the past.

"In our next round of proposals, we plan to go star-by-star. We will say, 'We have this much data on this individual star, and from that data we can determine the following things….'"

Allegheny also hopes to incorporate data it's collected over the last 85 years with new NASA information in the search for new planets. "One of the drawbacks of satellite-based telescope projects is that they usually only fly for about five years," Gatewood said. "That isn't long enough to detect 'wobbles' in very slow orbits. But if you combined the data from our plates with the data that will come from the FAME project, it would give us something like 90 years' worth of observations."

In addition to analyzing data from space telescopes, Allegheny Observatory hopes to continue training scientists to use astronomical equipment, and to become a site where new equipment is developed for use in space, Gatewood said.

"We also will continue as a tour facility for the people of Pittsburgh, which was one of the observatory's main purposes when it was built," he said.

As for Allegheny's showpiece, the Thaw refractor (with its 14-year-old lenses and instrumentation, added to the original 87-year-old telescope tube and mount), Gatewood said: "I would foresee that it will be used in conjunction with the satellite telescopes and our computer analysis work for at least the next decade. Beyond that, it's difficult to say."

Gatewood said the 47-foot-long telescope is unique: a large refractor that works in the red part of the light spectrum. "That means it works well in a city environment," he explained. "When you look at the red part of the spectrum, the sky over Pittsburgh is quite dark. It's almost like being out in the country.

"Former Chancellor [Wesley] Posvar used to enjoy telling people that we got our best images when the air was most polluted. And that, as a matter of fact, was true." When the air is still, it causes inversions that trap pollution in the valley below Observatory Hill, Gatewood explained. "We sit just above that, where the air is clearer. And, because the air is steady, we get a very sharp image."

— Bruce Steele

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