skip to main content


Title: WISE Photometry for 400 million SDSS sources

Here, we present photometry of images from the Wide-Field Infrared Survey Explorer (WISE) of over 400 million sources detected by the Sloan Digital Sky Survey (SDSS). We also use a "forced photometry" technique, using measured SDSS source positions, star-galaxy classification, and galaxy profiles to define the sources whose fluxes are to be measured in the WISE images. We perform photometry with The Tractor image modeling code, working on our "unWISE" coaddds and taking account of the WISE point-spread function and a noise model. The result is a measurement of the flux of each SDSS source in each WISE band. Many sources have little flux in the WISE bands, so often the measurements we report are consistent with zero given our uncertainties. But, for many sources we get 3σ or 4σ measurements; these sources would not be reported by the "official" WISE pipeline and will not appear in the WISE catalog, yet they can be highly informative for some scientific questions. In addition, these small-signal measurements can be used in stacking analyses at the catalog level. The forced photometry approach has the advantage that we measure a consistent set of sources between SDSS and WISE, taking advantage of the resolution andmore » depth of the SDSS images to interpret the WISE images; objects that are resolved in SDSS but blended together in WISE still have accurate measurements in our photometry. Our results, and the code used to produce them, are publicly available at« less
 [1] ;  [2] ;  [3]
  1. Univ. of Toronto, ON (Canada). Dept. of Astronomy and Astrophysics and Dunlap Inst.; Univ. of Waterloo, ON (Canada). Dept. of Physics and Astronomy
  2. New York Univ. (NYU), NY (United States). Center for Cosmology and Particle Physics; Max Planck Inst. for Astronomy, Heidelberg (Germany)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Astronomical Journal (Online)
Additional Journal Information:
Journal Name: Astronomical Journal (Online); Journal Volume: 151; Journal Issue: 2; Journal ID: ISSN 1538-3881
IOP Publishing - AAAS
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS; catalogs; methods: data analysis; surveys; techniques: image processing
OSTI Identifier: