J/AJ/132/926 Galaxies in the Hubble Ultra Deep Field (Coe+, 2006)
Galaxies in the Hubble Ultra Deep Field.
I. Detection, multiband photometry, photometric redshifts, and morphology.
Coe D., Benitez N., Sanchez S.F., Jee M., Bouwens R., Ford H.
<Astron. J., 132, 926-959 (2006)>
=2006AJ....132..926C 2006AJ....132..926C
ADC_Keywords: Surveys ; Galaxies, photometry
Keywords: cosmology: observations - galaxies: distances and redshifts -
galaxies: evolution - galaxies: photometry - galaxies: statistics -
galaxies: structure
Abstract:
We present aperture-matched point-spread function (PSF)corrected
BVi'z'JH photometry and Bayesian photometric redshifts (BPZ) for
objects detected in the Hubble Ultra Deep Field (UDF), 8042 of which
are detected at the 10 level (e.g., i'<29.01 or z'<28.43). Most of
our objects are defined identically to those in the public STScI
catalogs, enabling a straightforward object-by-object comparison. We
have combined detections from i', z', J+H, and B+V+i'+ z'
images into a single comprehensive segmentation map. Using a new
program called SExSeg, we are able to force this segmentation map into
SExtractor for photometric analysis. The resulting photometry is
corrected for the wider NIC3 PSFs using our ColorPro software. We also
correct for the ACS z'-band PSF halo. Offsets are applied to our NIC3
magnitudes, which are found to be too faint relative to the ACS
fluxes. Based on BPZ spectral energy distribution (SED) fits to
objects of known spectroscopic redshift, we derived corrections of
-0.30±0.03mag in J and -0.18±0.04mag in H. Our offsets appear to
be supported by a recent recalibration of the UDF NIC3 images combined
with nonlinearity measured in NICMOS itself. The UDF reveals a large
population of faint blue galaxies (presumably young starbursts), bluer
than those observed in the original Hubble Deep Fields.
Description:
The UDF (03:32:39.0-27:47:29.1 [J2000.0]) was observed by the Wide
Field Camera (WFC) of HST ACS for a total of 400 orbits: 56 orbits
each in the B and V bands (F435W and F606W) and 144 orbits each in
i' and z' (F775W and F850LP)
We prune our catalog to the central 11.97arcmin2 of the ACS images,
which has at least half the average depth of the whole image. The B,
V, and i' UDF images are also ∼1.0, 0.9, and 1.4mag deeper than the
respective HDF images. A filter similar to z' was not available to
image the HDF, and its presence allows us to probe the UDF for i'-band
dropout galaxies at 5.7≲z≲7.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 86 18700 Detection catalog
table4.dat 95 18700 Photometric catalog
table5.dat 150 9069 Morphology in the i-band image
table7.dat 153 18700 Photometric redhifts (BPZ results)
UDFcat.fits 2880 1155 FITS version of UDFcat
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See also:
II/258 : Hubble Ultra Deep Field Catalog (UDF) (STScI, 2004)
J/AJ/130/1 : Catalog of source parameters in NICMOS UDF (Thompson+, 2005)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- [CBS2006] Number the corresponds to STScI catalogs (G1)
7- 8 I2 --- f_[CBS2006] [-1/6] Whether STScI segment was altered (2)
10- 17 F8.4 mag STidiff Our i MAG_ISO minus Beckwith's (3)
19- 24 I6 pix area Segment size
26- 37 F12.8 deg RAdeg Right Ascension in decimal degrees (J2000)
39- 50 F12.8 deg DEdeg Declination in decimal degrees (J2000)
52- 59 F8.2 pix Xpix x pixel coordinate in STScI ACS images
61- 68 F8.2 pix Ypix y pixel coordinate in STScI ACS images
70- 73 F4.2 --- wfcexp Depth in ACS image: 1=mean; we prune > 0.5
75- 81 F7.1 --- sig Significance of most significant detection
83- 86 F4.2 --- stel SExtractor stellarity in i-band (1=star)
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Note (2): Flag indicating whether STScI segment was altered:
0 = segment defined exactly as by STScI
-1 = some pixels removed (reassigned to different object(s))
1..6 = segment replaced by this many segments.
Note (3): Rough guide to degree of segment alteration.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- [CBS2006] Number that corresponds to STScI catalogs (G1)
7- 13 F7.3 mag Bmag ?=-99.000 ACS F435W band total AB magnitude (2)
15- 20 F6.3 mag e_Bmag ?=0.000 Error in Bmag
22- 28 F7.3 mag Vmag ?=-99.000 ACS F606W band total AB magnitude (2)
30- 35 F6.3 mag e_Vmag ?=0.000 Error in Vmag
37- 43 F7.3 mag imag ?=-99.000 ACS F775W band total AB magnitude (2)
45- 50 F6.3 mag e_imag ?=0.000 Error in imag
52- 58 F7.3 mag zmag ?=-99.000 ACS F850LP band total AB magnitude (2)
60- 65 F6.3 mag e_zmag ?=0.000 Error in zmag
67- 73 F7.3 mag Jmag ?=-99.000 NIC3 F110W band total AB magnitude (2)
75- 80 F6.3 mag e_Jmag ?=0.000 Error in Jmag
82- 88 F7.3 mag Hmag ?=-99.000 NIC3 F160W band total AB magnitude (2)
90- 95 F6.3 mag e_Hmag ?=0.000 Error in Hmag
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Note (2): NIC3 magnitudes are corrected to the PSF of the ACS images
(Section 3.3). We have also applied offsets of (J: -0.3±0.03,
H: -0.18±0.04) to the NIC3 magnitudes (Section 4.2.2).
99.00 = Non-detections (listed, for example, as 99.00±31.55) quote the
1σ detection limit of the aperture used on the given object.
-99.00 = unobserved magnitude; outside the NIC3 FOV or containing
saturated or other bad pixels.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- [CBS2006] Number that corresponds to Beckwith et al.
catalog (Cat. II/258, UDF NNNNN)
7- 18 F12.8 deg RAdeg Right Ascension in decimal degrees (J2000)
20- 31 F12.8 deg DEdeg Declination in decimal degrees (J2000)
33- 41 F9.2 --- chi2 Poorness of GALFIT fit
43- 47 F5.2 mag imag ?=99.00 ACS F775W band magnitude fit
49- 54 F6.2 mag e_imag ?=99.00 Error in imag
56- 61 F6.2 pix reff Effective radius
63- 69 F7.2 pix e_reff Error in reff
71- 77 F7.2 --- a/b Ellipticity a/b
79- 86 F8.2 --- e_a/b Error in a/b
88- 93 F6.2 deg PA [-90/90] Position angle
95-103 F9.2 deg e_PA Error in PA
105-108 F4.2 --- nser Sersic index n (f(r)∝r1/n)
110-116 F7.2 --- e_nser Error in nser
118-125 F8.2 pix Xpix Fit x pixel coordinate in STScI ACS images
127-134 F8.2 pix Ypix Fit y pixel coordinate in STScI ACS images
136-143 F8.2 pix Dist Distance between fit and Beckwith
coordinates (1)
145-150 F6.3 --- asym Asymmetry: image vs. 180-degree rotated
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Note (1): Dist restricted <2;
Dist>1000 indicates misfit.
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- [CBS2006] Number that corresponds to STScI catalogs (G1)
7- 12 F6.3 --- zb BPZ most likely redshift
14- 19 F6.3 --- zbmin Lower limit (95% confidence)
21- 26 F6.3 --- zbmax Upper limit (95% confidence)
28- 31 F4.2 --- tb BPZ most likely spectral type
33- 37 F5.3 --- odds Probability distribution, P(z), contained
within 2*0.06*(1+z)
39- 45 F7.3 --- chi2 Poorness of BPZ fit: observed vs. model fluxes
47- 53 F7.3 --- chi2b Modified chi2: model fluxes given error bars
55- 60 F6.2 --- zb1min ?=-1 Lower bound for highest peak in P(z) (2)
62- 67 F6.2 --- zb1max ?=-1 Upper bound for highest peak in P(z) (2)
69- 74 F6.3 --- odds1 ?=-1 Probability distribution, P(z),
within zb1min..zb1max (2)
76- 81 F6.2 --- zb2 ?=-1 BPZ 2nd-most-likely redshift (2)
83- 88 F6.2 --- zb2min ?=-1 Lower bound for 2nd-highest peak in P(z) (2)
90- 95 F6.2 --- zb2max ?=-1 Upper bound for 2nd-highest peak in P(z) (2)
97-101 F5.2 --- tb2 ?=-1 BPZ 2nd-most-likely spectral type (2)
103-108 F6.3 --- odds2 ?=-1 Probability distribution, P(z),
within zb2min..zb2max (2)
110-115 F6.2 --- zb3 ?=-1 BPZ 3rd-most-likely redshift (2)
117-122 F6.2 --- zb3min ?=-1 Lower bound for 3rd-highest peak in P(z) (2)
124-129 F6.2 --- zb3max ?=-1 Upper bound for 3rd-highest peak in P(z) (2)
131-135 F5.2 --- tb3 ?=-1 BPZ 3rd-most-likely spectral type (2)
137-142 F6.3 --- odds3 ?=-1 Probability distribution, P(z),
within zb3min..zb3max (2)
144-148 F5.2 --- L_zb Maximum Likelihood of most likely redshift
150-153 F4.2 --- L_tb Maximum Likelihood of most likely spectral type
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Note (2): If P(z) is multiply peaked; else -1
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Global notes:
Note (G1):
-- ID's <40000 correspond to Beckwith et al. 2003, Cat. II/258, UDF NNNNN
-- 40001-41271 correspond to Thompson et al. 2004, unpublished,
version 1 NIC3 image reductions and catalog.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 25-Apr-2008