WISE PHOTOMETRY FOR 400 MILLION SDSS SOURCES

By Dustin Lang, David W. Hogg, David Schlegel. 2014

172 citations recorded by the source corpus.

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 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. However, 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 and 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 http://unwise.me.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/ccc286bbc7630fb77cd44f6a6b2af4d637e784a2

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Citations in the corpus

The unWISE Catalog: Two Billion Infrared Sources from Five Years of WISE Imaging (2019, methodology): “…et al. 2017a, 2017b, 2018a), generated a new class of timedomain WISE coadds (Meisner et al. 2018b, 2018c), and performed forced photometry on these custom WISE coadds at the locations of more than a billion optically detected sources (Lang et al. 2014; Schlegel et al. 2015; Dey et al. 2018).”
GALEX–SDSS–WISE LEGACY CATALOG (GSWLC): STAR FORMATION RATES, STELLAR MASSES, AND DUST ATTENUATIONS OF 700,000 LOW-REDSHIFT GALAXIES (2016, methodology): “If we instead used 22 µm photometry from unWISE (Lang et al. 2016), the small scatter with respect to Rosario et al. (2016) Herschel+WISE IR luminosities of σ = 0.07 dex (Figure 3) would grow to σ = 0.14.”
The SDSS-IV Extended Baryon Oscillation Spectroscopic Survey: Baryon Acoustic Oscillations at Redshift of 0.72 with the DR14 Luminous Red Galaxy Sample (2017, methodology): “…stellar density, i-band depth, z-band sky flux, z-FWHM and r-band extinction, while two maps are derived from WISE photometry (Wright et al. 2010; Lang et al. 2014): median number of single-exposure frames per pixel in the WISE W1 band (WISE W1 Cov Med) and median of accumulated flux per pixel…”
Validation of the Scientific Program for the Dark Energy Spectroscopic Instrument (2023, methodology): “These models were also used to compute new photometric measurements in all four of the WISE bandpasses, as in Lang (2014); Lang et al. (2016b); Meis-ner et al. (2017).”
The Sloan Digital Sky Survey Reverberation Mapping Project: Sample Characterization (2018, methodology): “…DOUBLE arcsec Angular separation between SDSS and ALLWISE matches UNWISE1234 DOUBLE[4] mag Forced unWISE photometry at the SDSS position from Lang et al. (2016) UNWISE1234_ERR DOUBLE[4] mag Uncertainties in unWISE magnitudes BAL_FLAG LONG Broad absorption line flag; 0=nonBAL or no…”
Dust Attenuation Curves in the Local Universe: Demographics and New Laws for Star-forming Galaxies and High-redshift Analogs (2018, methodology): “Photometry is taken from unWISE catalog (Lang et al. 2016), which performed forced photometry on WISE images using SDSS centroids and profiles as priors.”
The Sloan Digital Sky Survey Quasar Catalog: Sixteenth Data Release (2020, methodology): “Additional imaging was incorporated from the Wide-field Infrared Survey Explorer (WISE; Wright et al. 2010) using the custom “unWISE” coadds (Lang et al. 2016).”
THE SDSS-IV EXTENDED BARYON OSCILLATION SPECTROSCOPIC SURVEY: QUASAR TARGET SELECTION (2015, methodology): “Force-photometer WISE imaging at the positions of the resulting sources using the Lang (2014) approach, or, equivalently, match to the forcephotometered catalog of Lang et al. (2014).”