J/A+A/598/A107       Candidate galaxy clusters in KiDS-DR2     (Radovich+, 2017)
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Searching for galaxy clusters in  the Kilo-Degree Survey.
    Radovich M., Puddu E., Bellagamba F., Roncarelli M., Moscardini L.,
    Bardelli S., Grado A., Getman F., Maturi M., Huang Z., Napolitano N.,
    McFarland J., Valentijn E., Bilicki M.
    <Astron. Astrophys. 598, A107 (2017)>
    =2017A&A...598A.107R        (SIMBAD/NED BibCode)
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ADC_Keywords: Clusters, galaxy ; Redshifts
Keywords: galaxies: clusters: general - galaxies: distances and redshifts

Abstract:
    In this paper, we present the tools used to search for galaxy clusters
    in the Kilo Degree Survey (KiDS), and our first results.

    The cluster detection is based on an implementation of the optimal
    filtering technique that enables us to identify clusters as
    over-densities in the distribution of galaxies using their positions
    on the sky, magnitudes, and photometric redshifts. The contamination
    and completeness of the cluster catalog are derived using mock
    catalogs based on the data themselves. The optimal signal to noise
    threshold for the cluster detection is obtained by randomizing the
    galaxy positions and selecting the value that produces a contamination
    of less than 20%. Starting from a subset of clusters detected with
    high significance at low redshifts, we shift them to higher redshifts
    to estimate the completeness as a function of redshift: the average
    completeness is ~85%. An estimate of the mass of the clusters is
    derived using the richness as a proxy.

Description:
    We present a catalog of 1543 candidate galaxy clusters found in the
    DR2 release of the Kilo-Degree Survey (KiDS), covering an area of 114
    sq. degrees, in the redshift range 0<=z<=0.7. Based on simulated data,
    we derived a completeness ~85% and a purity of at least 80%. The
    catalog also includes the position and magnitude of the galaxy
    identified as the BCG; an estimate of the cluster masses, which were
    computed using the number of candidate cluster member galaxies as a
    proxy. Due to the limited area available in KiDS DR2, the calibration
    of the richness-mass relation is still preliminary, and will be
    improved in the next releases.

File Summary:
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 FileName      Lrecl  Records   Explanations
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ReadMe            80        .   This file
clusters.dat     110     1543   Cluster positions and masses
                                 (corrected version, 27/03/2020)
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See also:
   II/344 : KiDS-ESO-DR2 multi-band source catalog (de Jong+, 2015)
   http://kids.strw.leidenuniv.nl/DR2 : kiDS DR2 Home Page

Byte-by-byte Description of file: clusters.dat
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   Bytes Format Units     Label     Explanations
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   1-  4  A4    ---        ---       [KDR2]
   6- 21  A16   ---        KDR2      Cluster name (JHHMMSS.s+DDMMSS)
  23- 29  F7.3  deg        RAdeg     Cluster Right Ascension (J2000)
  31- 37  F7.3  deg        DEdeg     Cluster Declination (J2000)
  39- 42  F4.2  ---        z         Photometric redshift of cluster
  44- 47  F4.1  ---        snr       Signal to noise of cluster detection
  49- 57  F9.5  deg        RABdeg    BCG Right Ascension (J2000)
  59- 67  F9.5  deg        DEBdeg    BCG Declination (J2000)
  69- 73  F5.2  mag        rmag      BCG r band magnitude
  75- 76  I2    ---        N500      Number of member galaxy candidates
                                      within R500
  78- 81  F4.2  Mpc        r500      Radius at Delta=500
  83- 86  F4.2 10+14Msun   M500      Cluster mass within r500
  88- 91  F4.2 10+14Msun e_M500      rms uncertainty on M500
  93- 95  I3    ---        N200      Number of member galaxy candidates
                                      within R500
  97-100  F4.2  Mpc        r200      Radius at Delta=200
 102-105  F4.2 10+14Msun   M200      Cluster mass within r200
 107-110  F4.2 10+14Msun e_M200      rms uncertainty on M200
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Acknowledgements:
    Mario Radovich, mario.radovich(at)oapd.inaf.it

References:
   de Jong J. et al.,  2015A&A...582A..62D,
   The first and second data releases of the Kilo-Degree Survey

History:
   07-Feb-2017: on-line version
   27-Mar-2020: corrected version, from author (some names corrected)

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(End)    Mario Radovich [INAF-OAPD, Italy], Patricia Vannier [CDS]   29-Dec-2016