August 1, 2001
Palomar Observatory Receives High-Speed Network Connectivity Via HPWREN:
Near-Earth Asteroid and Supernova Researchers Reap Benefits
More than 50 years have passed since astronomers first started using the Palomar Observatory's 48-inch Oschin telescope to study the night sky. Known throughout the world as the meter-class-aperture telescope with the largest field of view, the Oschin's most recent "claim to fame" is its link to an NSF-funded 45 Mbps network - the High Performance Wireless Research and Education Network (HPWREN).
Coupled with the Oschin's sophisticated digital camera, the high-speed network connection allows researchers to transmit real-time images directly from the observatory to worldwide astronomy laboratories. The images are primarily used for near-Earth asteroid research and supernova detection.
Near-Earth Asteroid Tracking (NEAT)
The Oschin telescope was first used for near-Earth asteroid and comet discovery by Eleanor Helin from the late 1970s to the early 1990s. Helin's research paved the way for today's near-Earth asteroid and comet researchers, who now estimate that there are approximately 500-1000 objects larger than one kilometer (0.6 mile) that approach the Earth within 48 million kilometers (30 million miles).
Even though most of these asteroids and comets will never pose a threat to Earth, there are a few that could eventually collide with our planet. Scientists with the NEAT project continue Helin's work and track the orbits of possibly hazardous near-Earth asteroids and comets.
"This newfound 45 megabits-per-second connection allows us to automatically transfer large images from the observatory to laboratories around the world," says Steve Pravdo, project leader for the NEAT program at the California Institute of Technology's Jet Propulsion Laboratory in Pasadena.
"We are also able to easily access data-intensive archival systems, which was really cumbersome - and often impossible - with a 56 kilobits-per-second dial-up modem," says Pravdo. "These archives let us compare current images with past images in real-time, which means that we are able to be more efficient in our efforts to discover and confirm potentially dangerous asteroids."
In only one month (July 2001), NEAT researchers discovered 16 near-Earth objects and one comet, and three of their discoveries were larger than one kilometer in diameter! Specifically, the scientists found 12 Amors (asteroids that approach the Earth's orbit from the outside), three Apollos (asteroids that cross the Earth's orbit), and one Aten (asteroids that approach the Earth's orbit from the inside).
|Palomar Connectivity Highlights
January 2001. A site survey was the first step toward establishing high-speed Internet access via HPWREN.
April 2001. After much planning, tower installation at the observatory begins.
May/June 2001. A relay site is configured atop Cuyamaca Mountains.
July 6, 2001. The connection is in place!
Caltech is also a partner in the Oschin program and plans to exploit the new database both with complementary observations at other telescopes and with scientific investigations.
The reference image, taken on June 16.
The search image, taken on June 30.
The subtraction between the reference and search images clearly illustrate the new supernova, coined by the International Astronomical Union (IAU) as Supernova 2001dd.
SN Image credits: Michael Wood-Vasey, LBNL, in collaboration with NEAT - JPL.
The Nearby Supernova Factory
Images captured by NEAT cameras are also used by researchers conducting supernova research. One group of supernova astrophysicists that are reaping great benefits from a combination of the NEAT images and the HPWREN connectivity work on an international collaboratory project called the Nearby Supernova Factory. These researchers hail from the Lawrence Berkeley National Laboratory (LBNL), the Laboratoire de Physique Nucleaire et de Haute Engergies de Paris, the Institut de Physique Nucleaire de Lyon, and the Centre de Recherche Astronomique de Lyon. "The Nearby Supernova Factory's goal is to discover nearby supernovae and study them in detail so that they can be used more effectively as cosmological distance indicators," explains Greg Aldering, a staff scientist at LBNL and project leader for the Nearby Supernova Factory.
That is, Aldering and his supernova research colleagues use their findings to measure distances to galaxies that are tens of billions of light years from Earth. Their most notable discovery was named Science Magazine's "Discovery of the Year" in 1998: the expansion of the Universe is accelerating! The cause of this expansion is currently unknown, however, some scientists believe that it is related to Einstein's famous Cosmological Constant and is commonly called "dark energy."
To measure the rate change of the universe's expansion due to "dark energy", astrophysicists must understand how the brightness of supernovae changes when their input ingredients change. This requires the researchers to discover the exploding supernovae as soon as possible - hence the real-time connectivity is crucial to their research efforts.
Not only is the real-time data an important factor in supernova research, but the amount of data required to conduct such studies is enormous. For instance, the supernova researchers currently have approximately eight terabytes of data within their database; however, this number is by no means stagnant. The database increases by 50 gigabytes daily!
"The immense amount of data collected by our group quickly overwhelms a telescope's disk arrays, so we rely on systems like the NERSC High Performance Storage System (HPSS) to deal with all of this data," says Aldering. "Conversely, we also needed a high-speed connection to the telescopes so that we could obtain the data in the first place."
With the 45 Mbps connection, Aldering and his colleagues can now transmit the collected data in real-time to their imaging archival system. This high-speed network allows the researchers to discover supernovae within hours of the imaging observations. As a result, the supernovae can then be further studied that same night - using the University of Hawaii's 88-inch telescope on Mauna Kea.
"By receiving access to the high-speed broadband connection, we are able to more efficiently advance our supernovae research," says Aldering, "and we hope to someday answer this most mysterious, yet fundamental, question about our Universe - the nature of dark energy."
Education and Outreach
In addition to the basic research conducted via HPWREN by Palomar Observatory researchers, astronomy education and outreach programs are also enhanced by the connectivity. Both graduate and undergraduate students working on the NEAT and Nearby Supernova Factory projects are able to witness the scientific discovery process on an hourly basis - as images with potentially new supernovae arrive at campus laboratories across the world via HPWREN from Palomar.
Students also participate in the analysis of near-Earth asteroids and comets, as well as supernovae light curves and spectra - often assisting with the development of scientific conclusions.
Additional photographs regarding Palomar Observatory are available at http://hpwren.ucsd.edu/Photos/sites.html#PO.
Bud Hale, who coordinated the Palomar Observatory installation, completes some tower work atop the Cuyamaca Mountains.
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