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Penn State Participates in the Release of The Largest Color Image of the Sky Ever Made

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11 January 2011
SDSSIII Image Release Schneider 1-2011

This illustration shows the wealth of information on scales both small and large available in the SDSS-III's new image. The picture in the top left shows the SDSS-III view of a small part of the sky, centered on the galaxy Messier 33 (M33). The middle top picture is a further zoom-in on M33, showing the spiral arms of this Galaxy, including the blue knots of intense star formation known as "HII regions." The top right-hand picture is a further zoom into M33 showing the object NGC604, which is one of the largest HII regions in that galaxy.

The figure at the bottom is a map of the whole sky derived from the galaxies SDSS-III image, divided into the northern and southern hemispheres of our galaxy. Visible in the map are the clusters and walls of that are the largest structures in the entire universe.
Larger images of the maps in the northern and southern galactic
hemispheres are available at: http://tinyurl.com/27tntqb and
http://tinyurl.com/25z4h3e Credit: M. Blanton and the SDSS-III

Today, the Sloan Digital Sky Survey-III (SDSS-III) is releasing the largest digital color image of the sky ever made, and it is free to all. The image has been put together over the last decade from millions of 2.8-megapixel images, creating a color image of more than a trillion pixels. This terapixel image is so big and detailed that 500,000 high-definition TVs would be needed to view it at its full resolution.

"The quality and the scope of this image are truly breathtaking," said Lawrence Ramsey, Head of Penn State's Department of Astronomy and Astrophysics and a member of the SDSS-III Advisory Council.

The new image is at the heart of new data being released by the SDSS-III collaboration at the 217th American Astronomical Society meeting in Seattle, Washington. This new SDSS-III data release, along with the previous data releases that it builds upon, gives astronomers the most comprehensive view of the night sky ever made. SDSS data already have been used to discover nearly a half-billion astronomical objects, including asteroids, stars, galaxies, and distant quasars. The latest, most precise positions, colors, and shapes for all these objects also are being released today. "This image provides opportunities for many new scientific discoveries in the years to come," explained Bob Nichol, a professor at the University of Portsmouth and Scientific Spokesperson for the SDSS-III collaboration.

Penn State is one of three Pennsylvania institutions, along with the University of Pittsburgh and Carnegie Mellon University, that have scientists involved in SDSS-III. Donald Schneider, a Distinguished Professor of Astronomy and Astrophysics at Penn State is the SDSS-III Survey Coordinator. Schneider is in charge of scheduling the observations of the SDSS-III survey.

"This is one of the biggest bounties in the history of science," said Mike Blanton from New York University, who is leading the SDSS-III data-archive work. Blanton and many other scientists have been working for months preparing the release of all these data, which will be a legacy for the ages, explained Blanton. Previous ambitious sky surveys, like the Palomar Sky Survey of the 1950s, still are being used as a reference, even today.

The image was started in 1998 using what was then the world's largest digital camera — a 138-megapixel imaging detector mounted on a dedicated 2.5-meter telescope at the Apache Point Observatory in New Mexico. Over the last decade, the Sloan Digital Sky Survey has scanned a third of the whole sky. This imaging camera is now being retired, and will be part of the permanent collection at the Smithsonian in recognition of its contributions to astronomy. "It has been wonderful to see the science results that have come from this camera," said Connie Rockosi, an astronomer from the University of California Santa Cruz, who started working on the camera in the 1990s as an undergraduate student with Jim Gunn, Professor of Astronomy at Princeton University and SDSS-I/II Project Scientist. "It's a bittersweet feeling to see this camera retired, because I've been working with it for nearly 20 years."

This enormous image is forming the basis for new surveys of the universe using the SDSS telescope. These surveys rely on spectra, an astronomical technique that uses instruments to spread the light from a star or galaxy into its component wavelengths. Spectra can be used to find the distances to distant galaxies, and to reveal the properties of different types of stars and galaxies — such as their temperature and chemical composition.

"We have upgraded the existing SDSS instruments, and we are using them to measure distances to over a million galaxies detected in this image," explains David Schlegel, an astronomer from Lawrence Berkeley National Laboratory and the Principal Investigator of the new SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). Schlegel explains that measuring distances to galaxies is more time-consuming than simply taking their picture, but in return, it provides a detailed three-dimensional map of the galaxies' distribution in space.

BOSS started taking data in 2009 and will continue until 2014. Once finished, BOSS will be the largest 3-D map of galaxies ever made, extending the original SDSS galaxy survey to a much larger volume of the universe.  The goal of BOSS is to precisely measure how so-called "Dark Energy" has changed over the recent history of the universe. These measurements will help astronomers understand the nature of this mysterious substance. "Dark energy is the biggest conundrum facing science today," Schlegel said.

Niel Brandt, Distinguished Professor of Astronomy and Astrophysics at Penn State and the leader of two of the BOSS science projects, is encouraged by the quality of the initial BOSS data. "The spectra of the quasars obtained by BOSS will allow us to investigate the physical conditions that exist near supermassive black holes," Brandt said.

In addition to BOSS, the SDSS-III collaboration has been studying the properties and motions of hundreds of thousands of stars in the outer parts of our Milky Way Galaxy. The survey, known as the Sloan Extension for Galactic Understanding and Exploration — or SEGUE — started several years ago but now has been completed as part of the first year of SDSS-III.

In conjunction with the image being released today, astronomers from SEGUE are also releasing the largest map of the outer Galaxy ever released. "This map has been used to study the distribution of stars in our Galaxy," said Rockosi, the principal investigator of SEGUE. "We have found many streams of stars that originally belonged to other galaxies torn apart by the gravity of our Milky Way. We've long thought that galaxies evolve by merging with others, now the SEGUE observations confirm this basic picture."

SDSS-III also is undertaking two other surveys of our Galaxy through 2014. The first, called MARVELS, will use a new instrument to repeatedly measure spectra for approximately 8500 nearby stars like our own Sun, looking for the tell-tale wobble caused by large Jupiter-like planets orbiting them. MARVELS is predicted to discover around a hundred new giant planets, and to possibly find a similar number of "brown dwarfs" that are intermediate between the most massive planets and the smallest stars.

Suvrath Mahadevan and Jason Wright, assistant professors of aAstronomy and astrophysics at Penn State, are using the Hobby-Eberly Telescope to perform detailed studies of the planets identified by MARVELS. "MARVELS is surveying an unprecendented number of stars for velocity variations, and we expect a steady stream of exciting discoveries over the next few years," Mahadevan said.

The second survey is the APO Galactic Evolution Experiment (APOGEE), which is using one of the largest infrared spectrographs ever built to undertake the first systematic study of stars in all parts of our Galaxy; even stars on the other side of our Galaxy beyond the central bulge. Such stars typically are difficult to study because their visible light is obscured by large amounts of dust in the disk of our Galaxy. However, by working at longer, infrared wavelengths, APOGEE can study them in great detail, thus revealing their properties and motions to explore how the different components of our Galaxy were put together.

"The SDSS-III is an amazingly diverse project built on the legacy of the original SDSS and SDSS-II surveys," Nichol said. "This image is the culmination of decades of work by hundreds of people, and it already has produced many incredible discoveries. Astronomy has a rich tradition of making all such data freely available to the public, and we hope everyone will enjoy it as much as we have."

[ D P S / B K K ]

Niel Brandt: nbrandt@astro.psu.edu, 814-865-3509
Suvrath Mahadevan: suvrath@astro.psu.edu, 814-865-0261
Lawrence Ramsey: lwr@astro.psu.edu, 814 865-0418
Donald Schneider: dps@astro.psu.edu, 814-863-9554
Barbara Kennedy (PIO): science@psu.edu, 814-863-4682

Michael Blanton, New York University, michael.blanton@gmail.com, 646-279-5098
Connie Rockosi, University of California Santa Cruz, crocoski@ucolick.org, 831-459-5246
David Schlegel, Lawrence Berkeley National Laboratory, djschlegel@lbl.gov, 510-495-2595
Bob Nichol, University of Portsmouth, SDSS-III Scientific Spokesperson, bob.nichol@port.ac.uk, +44 7963 792049
Jordan Raddick, SDSS-III Public Information Officer, raddick@jhu.edu, 443-570-7105

The SDSS-III collaboration announce today at the 217th American Astronomical Society (AAS) meeting the publication of Data Release Eight (DR8), which can be found at www.sdss3.org/dr8. All data published as part of DR8 are freely available to other astronomers, scientists and the public. Technical journal papers describing DR8 and the SDSS-III project were also released today on the arXiv e-Print archive, see [URL to come] The SDSS-III Collaboration (www.sdss3.org) includes many institutions from around the globe. 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 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, Brookhaven National Laboratory, University of Cambridge, University of Florida, the French Participation Group, the German Participation Group, the Instituto de Astrofisica de Canarias, the Michigan State/Notre Dame/JINA Participation Group, Johns Hopkins University, Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, New Mexico State University, New York University, the Ohio State University, the Penn State University, University of Portsmouth, Princeton University, the Spanish Participation Group, University of Tokyo, the University of Utah, Vanderbilt University, University of Virginia, University of Washington, and Yale University.

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