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The most ambitious attempt yet to trace the history of the universe has seen "first light." The Baryon Oscillation Spectroscopic Survey (BOSS), a part of the Sloan Digital Sky Survey III (SDSS-III), took its first astronomical data on the night of September 14-15 after years of preparations. That night, astronomers used the Sloan Foundation 2.5-meter telescope at Apache Point Observatory in New Mexico to measure the spectra of a thousand galaxies and quasars, thus starting a quest to eventually collect spectra for 1.4 million galaxies and 160,000 quasars by 2014.

Fig. 1: Photograph of Senior Operations Engineer Dan Long loading the first cartridge of the night into the Sloan Digital Sky Survey telescope. The cartridge holds a "plug-plates" at the top which then holds a thousand optical fibers shown in red and blue. These cartridges are locked into the base of the telescope and are changed many times during a night.
Photo credit: D. Long

Fig. 2: One of the "first light" spectra taken by the Baryon Oscillation Spectroscopic Survey (BOSS). The top panel shows the targeted blue quasar, highlighted in the image of the sky, which are thought to be supermassive black holes in distant galaxies. At the bottom is shown the BOSS spectrum of the object which allows astronomers to measure the "redshift", or distance to this object. BOSS plans to collect millions of such spectra and use their distances to map the geometry of the Universe.
Figure credit: D. Hogg, V. Bhardwaj and N. Ross
High resolution image at

"The data from BOSS will be the best ever obtained on the large-scale structure of the universe," said David Schlegel of the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab), the Principal Investigator of BOSS. BOSS uses the same telescope as the original Sloan Digital Sky Survey, but equipped with new, specially- built spectrographs to measure the spectra. The new spectrographs are much more efficient in infrared light, enabling them to look much farther back in time.

The ability to look further back in time is important in allowing BOSS to take advantage of a feature in the universe called "baryon oscillations." Baryon oscillations began when pressure waves traveled through the early universe. Like sound waves passing through air, the waves pushes some of the matter closer together as they travel. In the early universe, these waves were moving at half the speed of light, but when the universe was only a few hundred thousand years old, the universe cooled enough to halt the waves, leaving a signature 500 million light years in length.

"We can see these frozen waves in the distribution of galaxies today," said Daniel Eisenstein of the University of Arizona, the Director of the SDSS-III. "By measuring the length of the baryon oscillations, we can determine how dark energy has affected the expansion history of the universe. That in turn helps us figure out what dark energy could be. Studying baryon oscillations is thus an exciting method for measuring dark energy in a way that's complementary to techniques in supernova cosmology. BOSS's galaxy measurements will be a revolutionary dataset that will provide rich insights into the Universe."

The BOSS spectrographs will work with more than two thousand large metal plates that are placed at the focal plane of the telescope; these plates are drilled with the precise locations of nearly two million objects across the northern sky. Optical fibers plugged into a thousand tiny holes in each of these "plug plates" carry the light from each observed galaxy or quasar to BOSS's new spectrographs.

Using these plug plates for the first light image should have been easy, but it didn't quite turn out the way astronomers planned. "In our first test images, it looked like we'd just taken random spectra from all over," Schlegel said. After some hair-pulling, the problem turned out to be simple. "After we flipped the plus and minus signs in the program, everything worked perfectly."

"The first light spectra look remarkably good" said Guinevere Kauffmann, who leads a research group at the Max Planck Institute for Astrphysics in Germany that has been heavily involved in SDSS for more than 7 years. "We are very excited about the prospect of being able to push back in time, towards an epoch when galaxies and their black holes were much more active than they are today. Small numbers of spectra of high redshift galaxies are already available, but BOSS looks set to provide us with a quantum leap over what has gone before".

The first public data release from SDSS-III is planned for December 2010. The SDSS team has led the way in making high-quality astronomical data available to all on the Web, with no need to spend nights awake at a mountaintop telescope. The data continues to revolutionize astronomical science and education. Original SDSS data has already been used by others in thousands of research papers.

"This continues the legacy of the SDSS, one of the most productive astronomical surveys ever undertaken," said Jim Gunn of Princeton University, who will be awarded this month the National Medal for Science from President Obama for his pioneering work with the original SDSS. "The leadership of this next generation of the SDSS has passed to the young scientists who did most of the hard work in SDSS I and II, and they have done a wonderful job, quickly and well. Bravo!"


BOSS is the largest of four surveys in SDSS-III, which includes 350 scientists from 42 institutions. The BOSS design and implementation has been led from the U.S. Department of Energy's Lawrence Berkeley National Laboratory. The optical systems were designed and built at Johns Hopkins University, with new CCD cameras designed and built at Princeton University and the University of California at Santa Cruz/Lick Observatory. The University of Washington contributed new optical fiber systems, and Ohio State University designed and built an upgraded BOSS data-acquisition system. The "fully depleted" 16-megapixel CCDs for the red cameras evolved from Berkeley Lab research and were fabricated in Berkeley Lab's MicroSystems Laboratory (MSL).

Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy. The SDSS-III web site is linkPfeilExtern.gif

SDSS-III is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS-III Collaboration, including the University of Arizona, the Brazilian Participation Group, University of Cambridge, University of Florida, the French Participation Group, the German Participation Group, the Michigan State/Notre Dame/JINA Participation Group, Johns Hopkins University, the U.S. Department of Energy's Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, New Mexico State University, New York University, the Ohio State University, University of Portsmouth, Princeton University, University of Tokyo, the University of Utah, Vanderbilt University, University of Virginia, University of Washington and Yale University.


The Max Planck Institute for Astrophysics (MPA) joined the SDSS consortium in 2002. SDSS research at MPA has focused on understanding the physical properties of the local galaxy population, including their supermassive black holes. MPA scientists pioneered the development of new analysis techniques for deriving star formation rates, metallicities, mean stellar ages and black hole accretion rates using the high quality spectra provided by the survey.


In Germany:

Guinevere Kauffmann, SDSS Advisory Council Representative,
Max Planck Institute for Astrophysics,
Phone: +49-89-30000-2014

Martin Asplund, SDSS Collaboration Council Representative,
Max Planck Institute for Astrophysics,
Phone: +49-89-30000-2208

Other Countries:

David Schlegel, BOSS Principal Investigator,
Lawrence Berkeley National Laboratory,
Phone: +1 510-495-2595

Daniel Eisenstein, SDSS-III Director,
University of Arizona,
Phone: +1 520-621-5904

Bob Nichol, SDSS-III Spokesperson,
University of Portsmouth (UK),
Phone: +44 23 9284 3117

Paul Preuss, Communications Group,
Lawrence Berkeley National Laboratory,
Phone: +1 510-486-6249

Jordan Raddick, SDSS Public Information Officer,
Johns Hopkins University,
Phone: +1 410-516-8889

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last modified: 2010-8-23