Wireless network boosts supernova search to stellar first ye

by David Hart of the National Science Foundation

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In results presented this week at the 2003 meeting of the American Astronomical Society (AAS) in Seattle, astrophysicist Greg Aldering and colleagues report that their supernova factory project has discovered an unprecedented 34 new supernovae in its first year. The accomplishment would not have been possible without the National Science Foundation (NSF)-supported highperformance wireless network link to Palomar Observatory.

"This has been the best rookie year for any supernova search project," Aldering said. The Nearby Supernova Factory, led by Aldering at Lawrence Berkeley National Laboratory (LBNL), is seeking out 300 new exploding stars to be used as standard distance markers in future studies to measure the change in the universe's rate of expansion and thereby determine its dark energy content.

"We're completely dependent on the wireless network because we have to sift through huge amounts of images," Aldering said, "and we need those images as soon as possible after they're seen by the telescope."

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The High Performance Wireless Research and Education Network (HPWREN), a project of the University of California, San Diego, provides Caltech's Palomar Observatory with a high-speed link to the Internet. The link made it possible to amass the quartermillion images--six terabytes of compressed data--analyzed by Aldering and the Nearby Supernova Factory team in 2002.

Funded by the National Science Foundation, the federal agency that supports basic science and engineering research and infrastructure, HPWREN makes it possible to send images almost instantly from the 48-inch Oschin Telescope at Palomar's remote mountaintop site to a storage facility at the Department of Energy's National Energy Research Scientific Computing Center (NERSC), located at LBNL in Berkeley, CA. Each image is 16 megapixels, and three images are captured every 30 seconds. Fifty gigabytes, or nearly 80 CD-ROMs' worth, of raw data crosses the HPWREN link nightly.

Thanks to HPWREN, the project is likely to find many more supernovae in subsequent years, allowing the study of rare supernovae with unusual properties, which can better reveal how supernovae work, according to Aldering. The eventual collection of supernovae will be made available to the astronomy community.

"Greg's supernova findings clearly illustrate the benefits of astronomers and computer network researchers partnering as a team, and we are really pleased to see how much high-performance networks enable our collaborating scientists and educators," said HPWREN principal investigator Hans-Werner Braun of UCSD's San Diego Supercomputer Center. "We hope to continue our work together and intend to enhance the data communications bandwidth even more, as Greg and others have indicated that they can make even more great discoveries if they have more bandwidth available to them."

The supernova factory pipeline starts with images being collected by the NASA-funded Near-Earth Asteroid Tracking (NEAT) project. The images are sent across the 45-megabit-per-second HPWREN wireless link and on to LBNL, where NERSC's computers process the images to discover and rank supernova candidates. Eventually the pipeline will automate the entire discovery and confirmation process. Once a supernova is discovered from the Palomar images, follow-up observations will be obtained by remote control of the University of Hawaii's 88-inch telescope on Mauna Kea. The Hawaii observations will be shipped by Internet for image processing at a supercomputing center in France and then sent to NERSC for analysis.

"If we can do this quickly enough, we can even ask the Hawaii and Palomar telescopes to get more data, say, for a very rare type of transient object," Aldering said. "This is all supposed to happen automatically while we are asleep, although it will take a while to reach a reliable level of automation." The HPWREN team, led by Braun and Frank Vernon at the Scripps Institution of Oceanography, is prototyping and evaluating a non-commercial, high-performance, wide-area wireless network. The network includes backbone nodes on the UCSD campus and a number of hard-to-reach areas in San Diego County, including the Palomar and Mt. Laguna observatories, Native American communities, and several remote science field stations.