Princeton Weekly Bulletin June 22, 1998
N.M. telescope sees first light
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Provost Jeremiah Ostriker, who chaired the Astrophysical Sciences Department for many years and organized the consortium for the Sky Survey, expressed delight at the results. ''When I saw the incredibly beautiful images on the 30 foot scroll of stars, galaxies and nebulae produced by the first seven minutes of observation, I knew that it was worth the wait and the hard work of so many people, as well as the trust and support of those institutons -- Princeton prominent among them -- that backed this project from the beginning.''
Constance Rockosi '93, now a graduate student at the University of Chicago, reported the results at the June 8 meeting of the American Astronomical Society. She is a member of the team headed by Eugene Higgins Professor of Astronomy James Gunn that designed, built and installed the telescope's digital camera -- the most complex imaging instrument ever developed for astronomy.
The camera, which uses silicon charge-coupled devices to create five-color digital images of the sky, ''has come together in concept and in metal, glass and silicon over the past many years,'' said Gunn. ''It has of course been thoroughly tested in the lab, so we didn't really doubt that it would work on the sky. But the thrill of knowing that the survey is truly going to work, after so much sweat and tears of so many people, was quite incredible.''
100 million stars, galaxies
The telescope will also incorporate spectrographs built by scientists at Johns Hopkins University, which provide information about the chemical composition of the astronomical sources, and information about their distances to pinpoint their positions in three-dimensional space. The astronomers will use the images and spectra to construct the most comprehensive three-dimensional model of the cosmos ever attempted. Five years of datataking will produce a catalog of the positions and brightnesses of more than 100 million stars, galaxies and quasars.
''The Sky Survey will be significantly more sensitive than our current comprehensive guide to the heavens, the 40-year-old Palomar Sky Survey,'' said scientific director Bruce Margon of the University of Washington. ''It will map one quarter of the sky and give us a three-dimensional picture of the universe a hundred times greater than anyone has explored before.''
''The Sky Survey requires a novel computing and analysis environment,'' noted Hopkins astronomer Alex Szalay, who is designing data analysis systems for the project. ''This approach is creating new standards in data analysis for astronomy that may well apply to other fields -- such as the study of the human genome -- that require extra-ordinarily large data sets.''
Images on Internet
Data from the mountaintop will be transferred daily to computer systems at Fermilab near Chicago. Software systems called data pipelines will translate the raw data into images of the sky. Ultimately, the Sky Survey will be available to the public over the Internet. (The first light images can be seen now at www.sdss.org/sdss.html.) Professional and amateur astronomers, teachers and school-age astronomers will be able to dial up an image of a selected piece of the sky in five colors and eventually to conduct complex searches of the Sky Survey archives.
Princeton's three major responsibilities to the project are scientific oversight of system design, design and construction of the camera, and design and implementation of the software that processes the data from the camera.
In addition to Princeton, the University of Chicago, Fermilab, Hopkins and the Unviersity of Washington, the collaboration includes scientists from the Institute for Advanced Study, Japan Participation Group and U.S. Naval Observatory. Funding for the project has been provided by the Alfred P. Sloan Foundation, National Science Foundation and U.S. Department of Energy, as well as member institutions of the consortium.