The multi-object, fiber-fed spectrographs for the Sloan Digital Sky Survey and the Baryon Oscillation Spectroscopic Survey

Stephen A. Smee, James E. Gunn, Alan Uomoto, Natalie Roe, David Schlegel, Constance M. Rockosi, Michael A. Carr, French Leger, Kyle S. Dawson, Matthew D. Olmstead, Jon Brinkmann, Russell Owen, Robert H. Barkhouser, Klaus Honscheid, Paul Harding, Dan Long, Robert H. Lupton, Craig Loomis, Lauren Anderson, James AnnisMariangela Bernardi, Vaishali Bhardwaj, Dmitry Bizyaev, Adam S. Bolton, Howard Brewington, John W. Briggs, Scott Burles, James G. Burns, Francisco Javier Castander, Andrew Connolly, James R. A. Davenport, Garrett Ebelke, Harland Epps, Paul D. Feldman, Scott D. Friedman, Joshua Frieman, Timothy Heckman, Charles L. Hull, Gillian R. Knapp, David M. Lawrence, Jon Loveday, Edward J. Mannery, Elena Malanushenko, Viktor Malanushenko, Aronne James Merrelli, Demitri Muna, Peter R. Newman, Robert C. Nichol, Daniel Oravetz, Kaike Pan, Adrian C. Pope, Paul G. Ricketts, Alaina Shelden, Dale Sandford, Walter Siegmund, Audrey Simmons, D. Shane Smith, Stephanie Snedden, Donald P. Schneider, Mark SubbaRao, Christy Tremonti, Patrick Waddell, Donald G. York

Research output: Contribution to journalArticlepeer-review


We present the design and performance of the multi-object fiber spectrographs for the Sloan Digital Sky Survey (SDSS) and their upgrade for the Baryon Oscillation Spectroscopic Survey (BOSS). Originally commissioned in Fall 1999 on the 2.5 m aperture Sloan Telescope at Apache Point Observatory, the spectrographs produced more than 1.5 million spectra for the SDSS and SDSS-II surveys, enabling a wide variety of Galactic and extra-galactic science including the first observation of baryon acoustic oscillations in 2005. The spectrographs were upgraded in 2009 and are currently in use for BOSS, the flagship survey of the third-generation SDSS-III project. BOSS will measure redshifts of 1.35 million massive galaxies to redshift 0.7 and Lyα absorption of 160,000 high redshift quasars over 10,000 deg2 of sky, making percent level measurements of the absolute cosmic distance scale of the universe and placing tight constraints on the equation of state of dark energy. The twin multi-object fiber spectrographs utilize a simple optical layout with reflective collimators, gratings, all-refractive cameras, and state-of-the-art CCD detectors to produce hundreds of spectra simultaneously in two channels over a bandpass covering the near-ultraviolet to the near-infrared, with a resolving power R = λ/FWHM ~ 2000. Building on proven heritage, the spectrographs were upgraded for BOSS with volume-phase holographic gratings and modern CCD detectors, improving the peak throughput by nearly a factor of two, extending the bandpass to cover 360 nm < λ < 1000 nm, and increasing the number of fibers from 640 to 1000 per exposure. In this paper we describe the original SDSS spectrograph design and the upgrades implemented for BOSS, and document the predicted and measured performances.
Original languageEnglish
Article number32
Pages (from-to)32
JournalThe Astronomical Journal
Issue number2
Early online date12 Jul 2013
Publication statusPublished - Aug 2013


  • cosmology: observations
  • instrumentation: spectrographs
  • surveys


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