The nighttime sky looks deceptively tranquil. In reality it is alive with a variety of brief but violent outbursts popping on and off like July 4th fireworks. Stars explode in faraway galaxies and neutron stars hiccup in a burst of radiation as they devour companion stars. Mysterious blasts of gamma rays, possibly from collapsing black holes, zap earth from deep space.
Its a daunting task for astronomers to keep an eye on all these spectacular but totally unpredictable happenings. Yet, they are critical to understanding the most violent activities affecting our universe.
Needle in the haystack
Catching sight of these so-called transient phenomena is like looking for a needle in a haystack. An astronomer typically spends only a few nights per year looking at a selection of predetermined celestial targets. Aside from doing a tedious survey, coming across a cosmic "flash-in-the-pan" has been largely good luck -- being at the right place at the right time.
"This is a huge revolution in astronomy, where massive data processing, large format electronic imaging detectors...and the Internet have all suddenly come together to fundamentally change the way we explore the universe."
Enter the "robo-telecope" an autonomous, rapid response all-sky monitor, where silicon not only replaces the human eye, but largely the human brain. Like surveillance cameras in a department store, robo-telescopes, sitting alone and untended on isolated mountain tops, nightly patrol the sky, looking for any changes from the far corners of the universe. They move quickly and precisely, relying on their own onboard sky maps to prowl the heavens. The nightly flood of data is automatically archived and analyzed to note any changes in the present state-of-the universe.
Robo-telescopes are a boon to astronomers who want to catalog variable stars. They are ideal for studying supernovae (exploding stars) as well as the optical counterparts to gamma-ray bursts, the most powerful explosions known in the universe. And a host of other elusive and exotic phenomena are well suited to the robo-telescope concept.
Big bang of information for astronomers
The result has been a "big bang" of information for astronomers. Research that required over a decade of meticulous and patient observation can be now accomplished in a few months by these tireless, efficient sky sentinels. The nightly sky harvest has yielded huge databases of new phenomena that would have gone forever unnoticed by traditional human-tended observing techniques.
"This is a huge revolution in astronomy, where massive data processing, large format electronic imaging detectors (called charge-coupled devices, or CCDs), and the Internet have all suddenly come together to fundamentally change the way we explore the universe," said Jeffrey Bloch of the Los Alamos National Laboratory.
At Lick Observatory on Mt. Hamilton outside San Jose, Calif., a 30-inch mirror robotic telescope called the Katzman Automatic Imaging Telescope (KAIT) checks in on 1,000 galaxies every night. The telescope hunts for an elusive prey -- the flicker of light from a star that has self-destructed as a supernova. For a brief instant in the stars life it shines with the radiance of an entire galaxy.
Weather-check
Every night computers check the weather, automatically open the observatory dome, point and focus the telescope and take digital pictures. The images are sent via the Internet to a computer at the University of California at Berkeley, where they are compared automatically to earlier pictures of the same region of sky. Images with new points of light are flagged so that the next morning astronomers can double-check them and identify the best candidates.
Since it began operation in 1996, KAIT has pinpointed 70 supernovas in galaxies within 500 million light years of earth. "KAIT finds essentially all of the supernovas in the galaxies we monitor. We are surprised to find so many supernovas in such a short amount of time," says Alex Filippenko of UC Berkeley.
Filippenko and colleagues are building a much better idea of how common supernovas are, and how they vary in behavior. The supernovas are invaluable for studying the origin of elements, and the expansion rate of the universe.
Rapid-response sky hunter
Another rapid-respond sky hunter is the University of Michigans Robotic Optical Transient Search Experiment (ROTSE), consisting of four telephoto photographic lenses mounted on CCDs. When a gamma-ray burst goes off, its position as measured by a constellation of satellites is automatically and instantly relayed to ROTSE. Within three seconds of the receipt of this information ROTSE pivots to the target position, and begins snapping off pictures to pinpoint the rapidly fading optical fireball resulting from the burst.
The largest robotic telescope so far is the 80-inch Liverpool Robotic Telescope, which is now under construction. It will be located in La Palma in the Canary Islands, and monitored from a control center 2000 miles away in the United Kingdom. "Its like having a space probe on the ground" Michael Bode of the Liverpool John Moores University told Space.Com. If an astronomer needs the telescope to look at something special that night, it can be re-programmed via the Internet to halt its planned observing schedule and go looking off in another direction.
Bodes goal is to ultimately build "RoboNet" six duplicate telescopes equally spaced around the globe. Tied together by the Internet, they would provide non-stop coverage of any unfolding celestial drama. Such a "whole earth" telescope could look for planets beyond the sun by continuously monitoring the light from many stars simultaneously. A subtle and transitory brightening of a stars light would signal the passage of an intervening planet.
advertisement
