Looking in all the Right Places – The SLOAN DIGITAL SKY SURVEY Extends its Reach

July 17, 2014

Building on the past successes, the Sloan Digital Sky Survey (SDSS) collaboration has launched a major new program that will expand the census of the Universe into new areas. The new survey is a collaboration of more than 200 astronomers at more than 40 institutions on four continents, and incorporates telescopes in both the Northern and Southern Hemispheres to explore the entire sky for the first time.

Over the last fourteen years, many astronomers have used SDSS data to make numerous discoveries related to the large-scale structure of the Universe, the secrets of distant Quasars, the Milky Way or even solar system objects.

"MPIA was the first European partner institute in SDSS and the only one to participate since the inception of the survey", says MPIA director Hans-Walter Rix. "The new phase of SDSS will provide a vast new database of observations that will significantly expand our understanding of the Milky Way and of the nature of the Universe at all scales".

Measuring the compositions, positions, and motions of individual stars will reveal how our Milky Way Galaxy evolved from the distant past to today. Using two telescopes in both hemispheres – the Sloan Foundation 2.5-meter Telescope in New Mexico and now also the 2.5-meter Irenee du Pont Telescope at Las Campanas Observatory in Chile – will finally provide a consistant 360-degree view of the Milky Way.

Detailed maps of thousands of near and moderate distant galaxies will be used to determine their evolution over billions of years. This will be possible with a new cutting-edge measurement device consisting of bundling sets of fiber optic cables collecting light from across the entire faces of more than 10.000 galaxies.

Furthermore, a new set of very distant galaxies and quasars will allow astronomers to precisely measure the expansion history of the universe through 80% of cosmic history, helping to improve constraints on the nature of the mysterious dark energy.

The original press release of the SDSS Consortium can be found here

Figure 1: The new SDSS will measure spectra at multiple points in the same galaxy, using a newly created fiber bundle technology. The left-hand side shows the Sloan Foundation Telescope and a close-up of the tip of the fiber bundle. The bottom right illustrates how each fiber will observe a different section of each galaxy. The image (from the Hubble Space Telescope) shows one of the first galaxies that the new SDSS has measured. The top right shows data gathered from two fibers observing two different parts of the galaxy, showing how the spectrum of the central regions differs dramatically from outer regions.
Figure 2: SDSS-IV will extend its reach by using both the Sloan Foundation Telescope at Apache Point Observatory and the du Pont telescope at Las Campanas Observatory in Chile, as shown on the left.
Because of the orientation of the Earth's axis relative to the disk of the Milky Way, the northern telescope will observe a very different part of the Milky Way (shaded in blue) than the southern telescope (shaded in green), which will have an excellent view of the galactic center regions. The nested spheres show the range of distances from the Sun that the survey of the Milky Way will reach, depending on survey strategy and the density of stars and dust along the line-of-sight. Some observations will reach to the innermost sphere, while the deepest observations will extend to the outermost sphere and our neighboring dwarf galaxies, the Magellanic Clouds, shown at the bottom of the image.
Figure 3: Previously, SDSS has mapped the universe across billions of light-years, focusing on the time from 7 billion years after the Big Bang to the present and the time from 2 billion years to 3 billion years after the Big Bang. SDSS-IV will focus on mapping the distribution of galaxies and quasars 3 billion years to 7 billion years after the Big Bang, a critical time when dark energy is thought to have started to affect the expansion of the Universe.

Changing a cartridge, opening the enclosure, sunset, and nightly observing at the Sloan Foundation 2.5m Telescope at Apache Point Observatory, Sunspot, New Mexico.
During the night, an observer changes the cartridge to observe a new set of stars or galaxies roughly every hour. Each cartridge contains hundreds of fiber-optic cables plugged into holes in a large aluminum plate. Each fiber observes a single star or galaxy.
The "bright time" observing is during full moon, the "dark time" is before moonrise, with the moon (not the sun!) rising shortly before the end of the video. The orange glow in the background is from the city of El Paso, Texas, 90 miles to the south.
The lights briefly shining through the telescope petals before and after cartridge changes are calibration sequences. We use different light sources to check that all parts of the instrument see light the same way and to compare the observations to known standards.

Credit: John Parejko (Yale University) and the SDSS collaboration
[Video on Youtube]


Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation and the Participating Institutions. SDSS-IV acknowledges support and resources from the Center for High-Performance Computing at the University of Utah. The SDSS web site is www.sdss.org.

SDSS-IV is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS Collaboration including the Carnegie Institution for Science, Carnegie Mellon University, the Chilean Participation Group, Harvard-Smithsonian Center for Astrophysics, Instituto de Astrofisica de Canarias, The Johns Hopkins University, Kavli Institute for the Physics and Mathematics of the Universe (IPMU) / University of Tokyo, Lawrence Berkeley National Laboratory, Leibniz Institut für Astrophysik Potsdam (AIP), Max-Planck-Institut für Astrophysik (MPA Garching), Max-Planck-Institut für Extraterrestrische Physik (MPE), Max-Planck-Institut für Astronomie (MPIA Heidelberg), National Astronomical Observatory of China, New Mexico State University, New York University, The Ohio State University, Pennsylvania State University, Shanghai Astronomical Observatory, United Kingdom Participation Group, Universidad Nacional Autonoma de Mexico, University of Arizona, University of Colorado Boulder, University of Portsmouth, University of Utah, University of Washington, University of Wisconsin, Vanderbilt University, and Yale University.


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Different versions of this image for download

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