J/MNRAS/453/1136 XDF CHEF photometric catalogue (Jimenez-Teja+, 2015)
Accurate PSF-matched photometry and photometric redshifts for the extreme deep
field with the Chebyshev-Fourier functions.
Jimenez-Teja Y., Benitez N., Molino A., Fernandes C.A.C.
<Mon. Not. R. Astron. Soc., 453, 1136-1146 (2015)>
=2015MNRAS.453.1136J 2015MNRAS.453.1136J (SIMBAD/NED BibCode)
ADC_Keywords: Galaxy catalogs ; Galaxies, photometry ; Redshifts
Keywords: methods: data analysis - astronomical data bases: catalogues -
techniques: photometric - galaxies: distances and redshifts -
galaxies: photometry
Abstract:
Photometric redshifts, which have become the cornerstone of several of
the largest astronomical surveys like PanStarrs, DES, J-PAS and LSST,
require precise measurements of galaxy photometry in different bands
using a consistent physical aperture. This is not trivial, due to the
variation in the shape and width of the point spread function (PSF)
introduced by wavelength differences, instrument positions and
atmospheric conditions. Current methods to correct for this effect
rely on a detailed knowledge of PSF characteristics as a function of
the survey coordinates, which can be difficult due to the relative
paucity of stars tracking the PSF behaviour. Here we show that it is
possible to measure accurate, consistent multicolour photometry
without knowing the shape of the PSF. The Chebyshev-Fourier functions
(CHEFs) can fit the observed profile of each object and produce high
signal-to-noise integrated flux measurements unaffected by the PSF.
These total fluxes, which encompass all the galaxy populations, are
much more useful for galaxy evolution studies than aperture
photometry. We compare the total magnitudes and colours obtained using
our software to traditional photometry with SExtractor, using real
data from the COSMOS survey and the Hubble Ultra-Deep Field (HUDF). We
also apply the CHEF technique to the recently published eXtreme Deep
Field (XDF) and compare the results to those from ColorPro on the
HUDF. We produce a photometric catalogue with 35732 sources (10823
with signal-to-noise ratio ≥5), reaching a photometric redshift
precision of 2 per cent due to the extraordinary depth and wavelength
coverage of the eXtreme Deep Field images.
Description:
In Jimenez-Teja & Benitez (2012ApJ...745..150J 2012ApJ...745..150J), we presented an
analytical formula to measure the flux just using the CHEF
coefficients. Now we implement this calculation into an algorithm that
maximizes the capabilities of the CHEF decomposition and incorporates
the effect of the PSF without computing it nor applying any kind of
correction. The basic idea is to evaluate the CHEF models within a
frame large enough to enclose all the flux from a galaxy, determining
the radius up to which the object extends and measuring its total
magnitude. This will provide a PSF-independent measurement of the
magnitude, which can be compared across filters, avoiding the
time-consuming determination of the PSF and the possible errors
introduced by it.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 289 35802 CHEF photometric catalogue
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- ID SExtractor identification number
7- 15 F9.6 deg RAdeg Right ascension of barycenter (J2000)
17- 26 F10.6 deg DEdeg Declination of barycenter (J2000)
28- 36 F9.6 mag F105W ?=99.000000 Total magnitude for F105W filter
38- 49 F12.6 mag e_F105W ?=31.117068 Error in F105W
51- 59 F9.6 mag F125W ?=99.000000 Total magnitude for F125W filter
61- 73 F13.6 mag e_F125W ?=30.808307 Error in F125W
75- 83 F9.6 mag F140W ?=99.000000 Total magnitude for F140W filter
85- 96 F12.6 mag e_F140W ?=28.732280 Error in F140W
98-106 F9.6 mag F160W ?=99.000000 Total magnitude for F160W filter
108-119 F12.6 mag e_F160W ?=30.463811 Error in F160W
121-129 F9.6 mag F435W ?=99.000000 Total magnitude for F435W filter
131-143 F13.6 mag e_F435W ?=30.773222 Error in F435W
145-153 F9.6 mag F606W ?=99.000000 Total magnitude for F606W filter
155-166 F12.6 mag e_F606W ?=31.421360 Error in F606W
167 A1 --- neF606W [i] i for infinity
168-176 F9.6 mag F775W ?=99.000000 Total magnitude for F775W filter
178-189 F12.6 mag e_F775W ?=31.252622 Error in F775W
190 A1 --- neF775W [i] i for infinity
191-199 F9.6 mag F814W ?=99.000000 Total magnitude for F814W filter
201-211 F11.6 mag e_F814W ?=30.054007 Error in F814W
213-221 F9.6 mag F850LP ?=99.000000 Total magnitude for F850LP filter
223-233 F11.6 mag e_F850LP ?=30.499898 Error in F850LP
235-242 F8.6 --- zb [0/7] Best BPZ photometric redshift estimation
244-251 F8.6 --- zbmin [0/7] Lower limit for 1sigma confidence
interval
253-260 F8.6 --- zbmax [0/7] Upper limit for 1sigma confidence
interval
262-270 F9.6 --- tb [1/11] Best BPZ spectral type estimation
272-279 F8.6 --- Odds [0/1] Photometric redshift reliability
281-289 F9.6 --- Chi2 Goodness of the BPZ fit
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 18-Mar-2016