University of Barcelona


Organization: SDSS Collaboration
Start operation: 2000
Project length: 5+3+6+6 years
Location: Apache Point Observatory, New Mexico
Instrumentation: 1 photometric system, 2 spectrographs
Wavelength: Optical
Diameter: 2.5 m
Website: SDSSIII Web site

The Sloan Digital Sky Survey (SDSS) is an ambitious ongoing astronomy project that has been working since 1998 to make a detailed map of the Milky way, search for extrasolar planets, and solve the mystery of dark energy. The SDSS-III uses a dedicated 2.5-m wide angle optical telescope located at Apache Point Observatory (APO), in south east New Mexico. During nine years of operations of the first two survey programs, SDSS-I (2000-2005) and SDSS-II (2005-2008), deep, multi-color images were obtained covering more than a quarter of the sky, and 3-dimensional maps were created containing almost 1 million galaxies and more than 120,000 quasars. In 2008, SDSS third phase was started built on the legacy of the SDSS-I and SDSS-II. [-]

The telescope takes images using a photometric system of five filters, which are then processed to produce lists of objects observed and various parameters. The telescope is also equipped with a pair of spectrographs fed by optical fibers, which measure spectra of (and hence distances to) selected stars, galaxies and quasars. SDSS-III consists of four surveys executed on the same 2.5m telescope: the Apache Point Observatory Galactic Evolution Experiment (APOGEE) the Baryon Oscillation Spectroscopic Survey (BOSS), the Multi-Object APO Radial Velocity Exoplanet Large-area Survey (MARVELS), and the Sloan Extension for Galactic Understanding and Exploration 2 (SEGUE-2). These surveys focus on three scientific themes:

SDSS-III began in July 2008 and operated and released data until June 2014. Now, after the end of SDSS-III, the Sloan Foundation 2.5m Telescope at Apache Point Observatory will remain the world's premier wide-field spectroscopic facility. The Astrophysical Research Consortium (ARC) has been planning the next-generation SDSS (SDSS-IV) project taking advantage of this unique resource from 2014 through 2020.


The ICC ICREA researchers Licia Verde, Jordi Miralda and Raul Jiménez are closely related to the SDSS-III project. Licia Verde and Jordi Miralda are indeed part of the SDSS-III Collaboration. They are particularly involved in the BOSS project (SDSS-III's Baryon Oscillation Spectroscopic Survey), which is measuring Baryon Acoustic Oscillations using spectroscopic redshifts from a survey of Luminous Red Galaxies and from the Lyman Alpha Forest spectra in high-redshift quasars. Numerous contributions have been made by ICC graduate students and postdocs working in this ICC group deriving cosmological parameters and developing the methods to measure the large-scale structure distribution of galaxies and the intergalactic medium from the observational data obtained in the BOSS survey. [-]

A new international collaboration is also being organized that will address fundamental questions about physics and about the origins of stars and galaxies using the Sloan 2.5-m Telescope with new instrumentation and techniques to perform three optical and near-infrared spectroscopic surveys. The ICC is mostly interested in the one called the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). Using quasar and galaxy clustering, as well as Lyman-alfa forest observations at high redshift, eBOSS will measure the growth of structure and use the baryonic acoustic feature to measure the Universe’s expansion.