Improved background subtraction for the sloan digital sky survey images

Michael R. Blanton, Eyal Kazin, Demitri Muna, Benjamin A. Weaver, Adrian Price-Whelan

    Research output: Contribution to journalArticlepeer-review


    We describe a procedure for background subtracting Sloan Digital Sky Survey (SDSS) imaging that improves the resulting detection and photometry of large galaxies on the sky. Within each SDSS drift scan run, we mask out detected sources and then fit a smooth function to the variation of the sky background. This procedure has been applied to all SDSS-III Data Release 8 images, and the results are available as part of that data set. We have tested the effect of our background subtraction on the photometry of large galaxies by inserting fake galaxies into the raw pixels, reanalyzing the data, and measuring them after background subtraction. Our technique results in no size-dependent bias in galaxy fluxes up to half-light radii r 50 ∼ 100 arcsec; in contrast, for galaxies of that size the standard SDSS photometric catalog underestimates fluxes by about 1.5mag. Our results represent a substantial improvement over the standard SDSS catalog results and should form the basis of any analysis of nearby galaxies using the SDSS imaging data.

    Original languageEnglish (US)
    Article number31
    JournalAstronomical Journal
    Issue number1
    StatePublished - Jul 2011


    • atmospheric effects
    • galaxies: photometry
    • methods: data analysis
    • techniques: image processing

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science


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