The Multi-Object, Fiber-Fed Spectrographs for SDSS and the Baryon Oscillation Spectroscopic Survey
Creators: name: Smee, Stephen
name: Gunn, James E.
name: Uomoto, Alan
name: Roe, Natalie
name: Schlegel, David
name: Rockosi, Constance M.
name: Carr, Michael A.
name: Leger, French
name: Dawson, Kyle S.
name: Olmstead, Matthew D.
name: Brinkmann, Jon
name: Owen, Russell
name: Barkhouser, Robert H.
name: Honscheid, Klaus
name: Harding, Paul
name: Long, Dan
name: Lupton, Robert H.
name: Loomis, Craig
name: Anderson, Lauren
name: Annis, James
name: Bernardi, Mariangela
name: Bhardwaj, Vaishali
name: Bizyaev, Dmitry
name: Bolton, Adam S.
name: Brewington, Howard
name: Briggs, John W.
name: Burles, Scott
name: Burns, James G.
name: Castander, Francisco
name: Connolly, Andrew
name: Davenport, James R.
name: Ebelke, Garrett
name: Epps, Harland
name: Feldman, Paul D.
name: Friedman, Scott
name: Frieman, Joshua
name: Heckman, Timothy
name: Hull, Charles L.
name: Knapp, Gillian R.
name: Lawrence, David M.
name: Loveday, Jon
name: Mannery, Edward J.
name: Malanushenko, Elena
name: Malanushenko, Viktor
name: Merrelli, Aronne
name: Muna, Demitri
name: Newman, Peter
name: Nichol, Robert C.
name: Oravetz, Daniel
name: Pan, Kaike
name: Pope, Adrian C.
name: Ricketts, Paul G.
name: Shelden, Alaina
name: Sandford, Dale
name: Siegmund, Walter
name: Simmons, Audrey
name: Smith, D.
name: Snedden, Stephanie
name: Schneider, Donald P.
name: Strauss, Michael
name: SubbaRao, Mark
name: Tremonti, Christy
name: Waddell, Patrick
name: York, Donald G.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: 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 Lyman-alpha absorption of 160,000 high redshift quasars over 10,000 square degrees 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 &lt; λ&lt; 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.
description: 43 pages, 42 figures, revised according to referee report and accepted by AJ. Provides background for the instrument responsible for SDSS and BOSS spectra. 4th in a series of survey technical papers released in Summer 2012, including arXiv:1207.7137 (DR9), arXiv:1207.7326 (Spectral Classification), and arXiv:1208.0022 (BOSS Overview)