Spectroscopic Target Selection in the Sloan Digital Sky Survey: The Main Galaxy Sample

By M. Strauss, D. Weinberg, Robert Lupton, V. N. E. al.. 2002

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We describe the algorithm that selects the main sample of galaxies for spectroscopy in the Sloan Digital Sky Survey (SDSS) from the photometric data obtained by the imaging survey. Galaxy photometric properties are measured using the Petrosian magnitude system, which measures flux in apertures determined by the shape of the surface brightness profile. The metric aperture used is essentially independent of cosmological surface brightness dimming, foreground extinction, sky brightness, and the galaxy central surface brightness. The main galaxy sample consists of galaxies with r-band Petrosian magnitudes r ≤ 17.77 and r-band Petrosian half-light surface brightnesses μ50 ≤ 24.5 mag arcsec-2. These cuts select about 90 galaxy targets per square degree, with a median redshift of 0.104. We carry out a number of tests to show that (1) our star-galaxy separation criterion is effective at eliminating nearly all stellar contamination while removing almost no genuine galaxies, (2) the fraction of galaxies eliminated by our surface brightness cut is very small (∼0.1%), (3) the completeness of the sample is high, exceeding 99%, and (4) the reproducibility of target selection based on repeated imaging scans is consistent with the expected random photometric errors. The main cause of incompleteness is blending with saturated stars, which becomes more significant for brighter, larger galaxies. The SDSS spectra are of high enough signal-to-noise ratio (S/N > 4 per pixel) that essentially all targeted galaxies (99.9%) yield a reliable redshift (i.e., with statistical error less than 30 km s-1). About 6% of galaxies that satisfy the selection criteria are not observed because they have a companion closer than the 55″ minimum separation of spectroscopic fibers, but these galaxies can be accounted for in statistical analyses of clustering or galaxy properties. The uniformity and completeness of the galaxy sample make it ideal for studies of large-scale structure and the characteristics of the galaxy population in the local universe.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/c6fa193b4a3f2ce6607140b142096c1125633fbe

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Citations in the corpus

GALAXY ZOO: THE FUNDAMENTALLY DIFFERENT CO-EVOLUTION OF SUPERMASSIVE BLACK HOLES AND THEIR EARLY- AND LATE-TYPE HOST GALAXIES (2010, methodology): “The SDSS fibres are circular with a diameter of 3′′ (York et al. 2000; Strauss et al. 2002), which corresponds to a physical footprint of 1.2 – 2.9 kpc in diameter at the lower and upper redshift limits of our sample.”
Galaxy ecology: groups and low-density environments in the SDSS and 2dFGRS (2003, background): “The upper redshift limit is that where our luminosity limit equals the magnitude limit of the SDSS (r = 17.7; Strauss et al. 2002).”
Active Galactic Nuclei in the Sloan Digital Sky Survey. II. Emission-Line Luminosity Function (2005, background): “…and photometry (Lupton et al. 2001), photometric calibration (Fukugita et al. 1996; Smith et al. 2002), spectroscopic target selection (Eisenstein et al. 2001; Strauss et al. 2002; Richards et al. 2002), spectroscopic fiber placement (Blanton et al. 2003a), and spectroscopic data reduction.”
Improved constraints on the expansion rate of the Universe up to z ∼ 1.1 from the spectroscopic evolution of cosmic chronometers (2012, methodology): “ETGs have been extracted from the SDSS-DR6 Main Galaxy Sample (MGS, [30]), matching SDSS photometry (u, g, r, i, and z) to 2MASS photometry (J , H, and K), in order to obtain a wider photometric coverage and extract robust mass estimates from the fitting of their photometric SEDs.”
Galaxy Zoo: the dependence of morphology and colour on environment (2008, methodology): “For our main analysis we consider only those galaxies in the Main Galaxy Sample, extended c© 2008 RAS, MNRAS000, 1–31 objects with rPetro < 17.77 (Strauss et al. 2002).”
On Departures from a Power Law in the Galaxy Correlation Function (2003, methodology): “…data reduction (R. H. Lupton et al. 2004, in preparation; see Lupton et al. 2001 and Stoughton et al. 2002 for summaries), and photometric calibration (Hogg et al. 2001; Smith et al. 2002), galaxies are selected for spectroscopic observations using the algorithm described by Strauss et al. (2002).”
ROBUST OPTICAL RICHNESS ESTIMATION WITH REDUCED SCATTER (2011, methodology): “The mean color 〈c|z〉 = 0.625 + 3.149z was determined by matching maxBCG cluster members to the SDSS LRG (luminous red galaxy; Eisenstein et al. 2001) and “main” (Strauss et al. 2002) spectroscopic galaxy samples.”
Total Galaxy Magnitudes and Effective Radii from Petrosian Magnitudes and Radii (2005, methodology): “In the absence of measurement errors, all R1/4 light–profiles have exactly the same concentration index R90/R50 — the ratio of radii containing 90% and 50% of the Petrosian flux (e.g., Blanton et al. 2001; Strauss et al. 2002; Goto et al. 2003).”
GALAXY GROUPS IN THE SDSS DR4. III. THE LUMINOSITY AND STELLAR MASS FUNCTIONS (2008, methodology): “The magnitudes and colors of all galaxies are based on the standard SDSS Petrosian technique (Petrosian 1976; Strauss et al. 2002), have been corrected for galactic extinction (Schlegel, Finkbeiner & Davis 1998), and have been K-corrected and evolution corrected to z = 0.1, using the method…”
The SDSS DR6 luminosity functions of galaxies (2008, methodology): “The consequence of this limitation in the SDSS data is estimated in a 6% incompleteness by Strauss et al. (2002).”
The N2K Consortium. IV. New Temperatures and Metallicities for More than 100,000 FGK Dwarfs (2005, background): “Several of these large stellar catalogs are the Two Micron All Sky Survey (2MASS; Cutri et al. 2003), Tycho/Hipparcos (Perryman et al. 1997; Høg et al. 1998, 2000), and the Sloan Digital Sky Survey (SDSS) DR1 (Strauss et al. 2002; Abazajian et al. 2003), which contain very good flux measurements for”
Cosmological Parameters from Eigenmode Analysis of Sloan Digital Sky Survey Galaxy Redshifts (2004, methodology): “The SDSS Main Galaxy Sample (MGS; Strauss et al. 2002) will consist of spectra of nearly one million lowredshift (hzi 0:1) galaxies creating a three-dimensional map of local large-scale structure.”
What Aspects of Galaxy Environment Matter? (2006, background): “…2001); photometricity determination (Hogg et al. 2001); calibration (Fukugita et al. 1996; Smith et al. 2002); spectroscopic target selection (Eisenstein et al. 2001; Strauss et al. 2002; Richards et al. 2002); spectroscopic fiber placement (Blanton et al. 2003); and spectroscopic data reduction.”
The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: cosmological analysis of the DR12 galaxy sample (2016, methodology): “Below z = 0.2, the sample is affected by the bright limit of r > 16, and the BAO scale has been measured for z < 0.2 galaxies in the SDSS-I/II main galaxy redshift survey (Strauss et al. 2002) by Ross et al. (2015).”
Timing the starburst–AGN connection (2010, background): “In the local Universe, the Sloan Digital Sky Survey (SDSS) spectroscopic survey (York et al. 2000; Strauss et al. 2002; Abazajian et al. 2009) has provided the statistics necessary to calculate volumeaveraged quantities and to reveal which populations of AGN and galaxies are the sites of the…”
Galaxy Zoo Green Peas: discovery of a class of compact extremely star-forming galaxies (2009, background): “This is expected because thespectroscopic galaxy sample was selected to be both resolved and brighter than the faintest Pea (Strauss et al. 2002).”