SYNMAG PHOTOMETRY: A FAST TOOL FOR CATALOG-LEVEL MATCHED COLORS OF EXTENDED SOURCES

Obtaining reliable, matched photometry for galaxies imaged by different observatories represents a key challenge in the era of wide-field surveys spanning more than several hundred square degrees. Methods such as flux fitting, profile fitting, and PSF homogenization followed by matched-aperture phot...

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Bibliographic Details
Published in:The Astronomical journal 2012-12, Vol.144 (6), p.1-11
Main Authors: Bundy, Kevin, Hogg, David W, Higgs, Tim D, Nichol, Robert C, Yasuda, Naoki, Masters, Karen L, Lang, Dustin, Wake, David A
Format: Article
Language:English
Subjects:
ACCURACY
APERTURES
ASTRONOMY
ASTROPHYSICS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
DATA ANALYSIS
Fittings
Flux
GALAXIES
Homogenizing
Imaging
Mathematical models
PHOTOMETRY
RED SHIFT
Surveys
VISIBLE RADIATION
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Summary:Obtaining reliable, matched photometry for galaxies imaged by different observatories represents a key challenge in the era of wide-field surveys spanning more than several hundred square degrees. Methods such as flux fitting, profile fitting, and PSF homogenization followed by matched-aperture photometry are all computationally expensive. We present an alternative solution called "synthetic aperture photometry" that exploits galaxy profile fits in one band to efficiently model the observed, point-spread-function-convolved light profile in other bands and predict the flux in arbitrarily sized apertures. Because aperture magnitudes are the most widely tabulated flux measurements in survey catalogs, producing synthetic aperture magnitudes (SYNMAGs) enables very fast matched photometry at the catalog level, without reprocessing imaging data. We make our code public and apply it to obtain matched photometry between Sloan Digital Sky Survey ugriz and UKIDSS YJHK imaging, recovering red-sequence colors and photometric redshifts with a scatter and accuracy as good as if not better than FWHM-homogenized photometry from the GAMA Survey. Finally, we list some specific measurements that upcoming surveys could make available to facilitate and ease the use of SYNMAGs.
ISSN:0004-6256
1538-3881
1538-3881
DOI:10.1088/0004-6256/144/6/188