Tracking errant asteroids

By Diana Steele
News Office

In mid-March, Asteroid 1997 XF11 made headlines when astronomers announced that it might make an extremely close pass to earth 30 years from now. The next day, astronomers revised their predictions when old photographs showed that the asteroid's trajectory would take it farther from Earth than initially thought.

Identifying and tracking such asteroids has become a passionate pastime for a group of amateur astronomers working at the University's Yerkes Observatory. The group, Asteroid Search Science by Amateurs at Yerkes (ASSAY), was founded by last summer by Walter Wild, Senior Research Associate in Astronomy & Astrophysics.

"It's so incredible to be working at a facility like Yerkes," said ASSAY member George Buchwald, an electrical engineer at Motorola. "There isn't a night when I'm at Yerkes that I don't think about the history of the facility, the people who worked there and the science that was accomplished."

ASSAY was founded by Wild after the Planetary Society announced a request for proposals for asteroid searches. He approached the Northwest Suburban Astronomers group about undertaking such a search; they responded enthusiastically, and the group was awarded a $6,500 grant.

Since October, ASSAY has been preparing to undertake its search for near-Earth asteroids using the 24inch telescope at the Wisconsin observatory. The telescope has been recently refurbished, and by mid-April the project will be well under way.

ASSAY members include half a dozen engineers and other professionals at such companies as Motorola and Lucent Technologies. "All of the members of our group are amateur astronomers who are professionals in science-related fields," Buchwald said. "When we first began showing up at Yerkes, I thought we wouldn't be accepted. In fact, just the opposite happened, and we have formed some very good relationships there."

The arrangement benefits the professional astronomers as well, Wild said. "The amateurs really show a lot of enthusiasm, and they help us out quite a bit," he said. "They bring a lot of expertise in software, mechanical and electrical engineering."

For the asteroid search, Buchwald and the other members will take images of six areas of the sky twice a week, and compare them to catalogues of the sky, looking for anything moving relative to the stars. Once several images have been taken that show the same object, its trajectory can be calculated.

Under Wild's direction, ASSAY also plans to use the 41-inch telescope to study Jovian seismology, as well as refurbishing a spectrograph that Yerkes obtained when the observatory at Northwestern University was demolished.

Wild said future plans include helping to develop a "cookbook" adaptive optics system that could be built for $5,000 to $10,000, instead of the millions of dollars such systems cost today. Adaptive optics systems, which use a deformable mirror to compensate for atmospheric turbulence (which causes the "twinkling" of starlight), can produce images from ground-based telescopes that rival those taken in space.

ASSAY members share a keen interest in astronomy. Buchwald and his wife have three telescopes of their own, including one 25-inch telescope that he hauls around in a camping trailer to places with dark skies.

"I have had an interest in astronomy since I was very young -- I grew up in the generation that watched man go to the moon," said Buchwald. "After starting my professional career, it became a passion and an escape, one that my wife, Vicki, and I both enjoy together. Working at Yerkes is incredible. To be able to go up there and open the dome and point the telescope at a section of the sky is amazing."

For more information about Yerkes Observatory, including information about visiting hours and tours, see astro.uchicago.edu/Yerkes.html.