J/AJ/125/2064 Northern Optical Cluster Survey. II. (Gal+, 2003)
The northern optical cluster survey.
II. An objective cluster catalog for 5800 square degrees.
Gal R.R., de Carvalho R.R., Lopes P.A.A., Djorgovski S.G., Brunner R.J.,
Mahabal A., Odewahn S.C.
<Astron. J. 125, 2064 (2003)>
=2003AJ....125.2064G 2003AJ....125.2064G
ADC_Keywords: Surveys ; Clusters, galaxy ; Redshifts
Keywords: catalogs - galaxies: clusters: general -
large-scale structure of universe - surveys
Abstract:
We present a new, objectively defined catalog of candidate galaxy
clusters based on the galaxy catalogs from the digitized Second
Palomar Observatory Sky Survey. This cluster catalog, derived from the
best calibrated plates in the high-latitude (|b|>30°) northern
Galactic cap region, covers 5800deg2 and contains 8155 candidate
clusters. A simple adaptive kernel density mapping technique, combined
with the SExtractor object detection algorithm, is used to detect
galaxy overdensities, which we identify as clusters. Simulations of
the background galaxy distribution and clusters of varying richnesses
and redshifts allow us to optimize detection parameters and measure
the completeness and contamination rates for our catalog. Cluster
richnesses and photometric redshifts are measured, using integrated
colors and magnitudes for each cluster. An extensive spectroscopic
survey is used to confirm the photometric results. This catalog, with
well-characterized sample properties, provides a sound basis for
future studies of cluster physics and large-scale structure.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table6.dat 58 8155 The Northern Sky Cluster Catalog
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See also:
J/ApJS/129/435 : NORAS galaxy cluster survey. I. (Bohringer+, 2000)
J/ApJS/115/1 : MX northern Abell cluster redshift survey (Slinglend+ 1998)
J/AJ/128/1017 : Northern Optical Survey. IV. (Lopes+, 2004)
Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [NSC]
5- 18 A14 --- NSC Cluster designation, JHHMMSS+DDMMSS (1)
20- 28 F9.5 deg RAdeg Right ascension expressed in degrees (J2000)
30- 37 F8.5 deg DEdeg Declination expressed in degrees (J2000)
39- 44 F6.4 --- z Photometric redshift estimate (2)
45 A1 --- u_z [:] Uncertainty flag
47- 51 F5.1 --- Ngals Measured richness (3)
53- 54 I2 --- Nmaps Number of simulated maps in which the cluster
was detected (4)
56- 58 I3 --- Plate POSS2 plate number from which the cluster is
drawn
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Note (1): The naming convention is NSC JHHMMSS+DDMMSS.
Note (2): If this is zero, the estimator failed to converge.
Note (3): If z>0.17, the correction factor γ, as described in
section 6.2, is applied.
Note (4): Only clusters detected in seven or more maps are included here.
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History:
From electronic version of the journal
References:
Gal et al., Paper I 2000AJ....119...12G 2000AJ....119...12G
Lopes et al., Paper IV 2004AJ....128.1017L 2004AJ....128.1017L, Cat. J/AJ/128/1017
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 06-Jun-2003