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S C I E N C E &
T E C H N O L O G Y
Taming the Terabyte
Collaborating to Map the Universe
The telescope for the Sloan Digital Sky Survey, at Apache Point,
New Mexico, will include two spectrographs that will record the
light coming from celestial objects across a wide range of the
electromagnetic spectrum. Instead of photographic plates, it will
contain charge-coupled devices (CCDs), the electronic light
sensors used in video cameras. Each star and galaxy will be
represented by roughly 1,000 pixels, but the sky will be viewed
through five different color filters, so there will be five
measurements per pixel. This all translates into a lot of data: a
grand total of about 40 terabytes of raw data, collected during
the five-year project, says Hopkins astronomer Alexander Szalay,
Sloan's archive director. The images will be digitized, recorded
on tapes, and transferred to Fermilab, outside Chicago.
Collaborating astronomers will then access the raw data through
vBNS, analyze it, and whittle down the results, saving the
distinct objects and tossing the rest. The finalized archive will
contain 1 terabyte, says Szalay, and will be placed on compact
discs (or a future technology) for public use within two
years.
--MH
Photo by Mike Ciesielski
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NOVEMBER 1997 TABLE OF CONTENTS.
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