Astronomical survey completes mission
15 August 2008 – After a decade of construction and eight years of operation (SDSS-I,2000-2005; SDSS-II, 2005-2008), the Sloan Digital Sky Survey (SDSS) completed its observations in mid-July and will release its final data set to the public in October. SDSS-III, a six-year programme composed of four new surveys, has now begun, using the same telescope.
“I’m glad we didn’t know at the beginning how hard it would be and how long it would take,” said SDSS Project Scientist Jim Gunn, the Princeton astronomer who has guided the project since its inception. “But now that we’ve finally accomplished what we set out to do, and much more besides, it seems worth all the effort and all the headaches along the way.”
The Sloan Digital Sky Survey is the most ambitious survey of the sky ever undertaken and involves over 300 astronomers and engineers at 25 institutions around the world. The University of Portsmouth and the
University of Cambridge are the only two British institutions to participate.
Using a dedicated 2.5-meter diameter telescope equipped with two specialized instruments, a 125-Megapixel digital camera and spectrographs that observe
640 stars and galaxies at a time, the SDSS has completed its original goals by making deep, multi-color images covering more than one-quarter of the sky and measuring the distances to nearly one million galaxies and over 100,000 quasars, thus creating the largest ever 3-dimensional maps of cosmic structure.
“What amazes me is the huge range of the discoveries that have come from SDSS data,” said SDSS-II Director Richard Kron, an astronomer at the University of Chicago and Fermilab. “We designed it primarily as a survey to map the distribution of galaxies and quasars, but it’s also had a huge impact on the study of stars, the structure of our own Galaxy, and even solar system objects.”
Those achievements are being celebrated this weekend at an international symposium titled “The Sloan Digital Sky Survey: Asteroids to Cosmology,” hosted by the Kavli Institute for Cosmological Physics at the University of
Chicago. In more than 80 presentations, astronomers from around the globe will describe new discoveries about stars, galaxies, and the cosmos, from the SDSS and from some of the other ambitious surveys that it helped inspire.
Astronomers are using the SDSS images and maps to understand the origins of galaxies and the properties of dark matter, the invisible material whose gravity binds stars together in galaxies. The gravity of dark matter also arranges the galaxies themselves into filamentary strands that span hundreds
of millions of light years, forming a network interleaved with low density tunnels and voids.