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Published September 2001 | Published + Submitted
Journal Article Open

Galaxy Number Counts from the Sloan Digital Sky Survey Commissioning Data

Abstract

We present bright galaxy number counts in five broad bands (u', g', r', i', z') from imaging data taken during the commissioning phase of the Sloan Digital Sky Survey (SDSS). The counts are derived from two independent stripes of imaging scans along the celestial equator, one each toward the northern and the southern Galactic cap, covering about 230 and 210 deg^2, respectively. A careful study is made to verify the reliability of the photometric catalog. For galaxies brighter than r* = 16, the catalog produced by automated software is examined against eye inspection of all objects. Statistically meaningful results on the galaxy counts are obtained in the magnitude range 12 ≤ r* ≤ 21, using a sample of 900,000 galaxies. The counts from the two stripes differ by about 30% at magnitudes brighter than r* = 15.5, consistent with a local 2 σ fluctuation due to large-scale structure in the galaxy distribution. The shape of the number counts–magnitude relation brighter than r* = 16 is well characterized by N ∝ 10^(0.6m), the relation expected for a homogeneous galaxy distribution in a "Euclidean" universe. In the magnitude range 16 < r* < 21, the galaxy counts from both stripes agree very well and follow the prediction of the no-evolution model, although the data do not exclude a small amount of evolution. We use empirically determined color transformations to derive the galaxy number counts in the B and I_(814) bands. We compute the luminosity density of the universe at zero redshift in the five SDSS bands and in the B band. We find L_B = 2.4 ± 0.4 × 10^8 L_⊙ h Mpc^(-3), for a reasonably wide range of parameters of the Schechter luminosity function in the B band.

Additional Information

© 2001 The American Astronomical Society. Received 2001 January 18; accepted 2001 May 16. Based on observations obtained with the Sloan Digital Sky Survey. Information available at http://www.sdss.org/. M. F. acknowledges support in Tokyo from a grant-in-aid from the Ministry of Education of Japan and in Princeton from the Raymond and Beverly Sackler Fellowship. M. A. S. acknowledges support from Research Corporation and NSF grants AST 96-18503 and AST 00-71091. I. S. was supported by the NASA grant NAG 5-3364. The Sloan Digital Sky Survey (SDSS) is a joint project of the University of Chicago, Fermilab, the Institute for Advanced Study, the Japan Participation Group, the Johns Hopkins University, the Max Planck Institute for Astronomy, New Mexico State University, Princeton University, the US Naval Observatory, and the University of Washington. Apache Point Observatory, site of the SDSS telescopes, is operated by the Astrophysical Research Consortium (ARC). Funding for the project has been provided by the Alfred P. Sloan Foundation, the SDSS member institutions, the National Aeronautics and Space Administration, the National Science Foundation, the Department of Energy, Monbusho, and the Max Planck Society.

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Published - Yasuda_2001_AJ_122_1104.pdf

Submitted - 0105545.pdf

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Created:
August 19, 2023
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October 20, 2023