J/ApJS/172/70       zCOSMOS-bright catalog                   (Lilly+, 2007)
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zCOSMOS: a large VLT/VIMOS redshift survey covering 0<z<3 in the COSMOS field.
    Lilly S.J., Fevre O.L., Renzini A., Zamorani G., Scodeggio M., Contini T.,
    Carollo C.M., Hasinger G., Kneib J.-P., Iovino A., Le Brun V., Maier C.,
    Mainieri V., Mignoli M., Silverman J., Tasca L.A.M., Bolzonella M.,
    Bongiorno A., Bottini D., Capak P., Caputi K., Cimatti A., Cucciati O.,
    Daddi E., Feldmann R., Franzetti P., Garilli B., Guzzo L., Ilbert O.,
    Kampczyk P., Kovac K., Lamareille F., Leauthaud A., Le Borgne J.-F.,
    Mccracken H.J., Marinoni C., Pello R., Ricciardelli E., Scarlata C.,
    Vergani D., Sanders D.B., Schinnerer E., Scoville N., Taniguchi Y.,
    Arnouts S., Aussel H., Bardelli S., Brusa M., Cappi A., Ciliegi P.,
    Finoguenov A., Foucaud S., Franceschini R., Halliday C., Impey C.,
    Knobel C., Koekemoer A., Kurk J., Maccagni D., Maddox S., Marano B.,
    Marconi G., Meneux B., Mobasher B., Moreau C., Peacock J.A., Porciani C.,
    Pozzetti L., Scaramella R., Schiminovich D., Shopbell P., Smail I.,
    Thompson D., Tresse L., Vettolani G., Zanichelli A., Zucca E.
   <Astrophys. J. Suppl. Ser., 172, 70-85 (2007)>
   =2007ApJS..172...70L
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ADC_Keywords: Surveys ; Redshifts
Keywords: cosmology: observations - galaxies: active -
          galaxies: distances and redshifts - galaxies: evolution -
          large-scale structure of universe - quasars: general - surveys

Abstract:
    zCOSMOS is a large-redshift survey that is being undertaken in the
    COSMOS field using 600hr of observation with the VIMOS spectrograph
    on the 8m VLT. The survey is designed to characterize the
    environments of COSMOS galaxies from the 100kpc scales of galaxy
    groups up to the 100Mpc scale of the cosmic web and to produce
    diagnostic information on galaxies and active galactic nuclei. The
    zCOSMOS survey consists of two parts:
    (1) zCOSMOS-bright, a magnitude-limited I-band I_AB_<22.5 sample of
    about 20000 galaxies with 0.1<z<1.2 covering the whole 1.7deg^2^
    COSMOS ACS field, for which the survey parameters at z~0.7 are
    designed to be directly comparable to those of the 2dFGRS at z~0.1;
    and (2) zCOSMOS-deep, a survey of approximately 10000 galaxies
    selected through color-selection criteria to have 1.4<z<3.0, within
    the central 1deg^2^.

    This paper describes the survey design and the construction of the
    target catalogs and briefly outlines the observational program and the
    data pipeline. In the first observing season, spectra of 1303
    zCOSMOS-bright targets and 977 zCOSMOS-deep targets have been
    obtained.

Description:
    A total of 10643 spectra could be extracted from the VIMOS
    observations and are presented in this release. Throughout the
    zCOSMOS-bright survey, 1arcsec wide slits have been used with a
    wavelength range of approximately 5500 to 9700{AA} sampled at roughly
    2.5{AA}/pixel.
    The primary input catalogue for slit-mask design was generated using
    SExtractor (Bertin et al., 1996A&AS..117..393B) applied to the COSMOS
    F814W HST/ACS images sampled at 0.03arcsec/pixel (Koekemoer et al.,
    2007ApJS..172..196K, Leauthaud et al., 2007ApJS..172..219L) in a "hot
    and cold" two-pass process to first identify bright objects. This
    substantially reduced the tendency of the HST-based catalogue to
    "over-resolve" extended galaxies into multiple components. This
    initial SExtractor catalogue was then "cleaned" by carrying out a
    detailed comparison with one extracted from a stack of i* images
    obtained with MEGACAM on the 3.6m Canada-France-Hawaii telescope and
    processed at the TERAPIX data reduction center in Paris. This
    catalogue was also used to supplement the ACS catalogue for regions
    where the ACS images were unavailable or unusable. The zCOSMOS-bright
    target catalogue is intended to be simply defined as having an ACS/HST
    SExtractor "magauto" brightness in the range 15.00<I_AB(814)_<22.50.

    Generally, objects to be inserted into the slit mask are chosen
    randomly from the target catalogue. However, a few percent of targets
    (generally X-ray sources) are designated as "compulsory" targets and
    inserted into the masks with first priority. As a result, they are
    over-represented in the spectroscopic catalogue, by a factor which
    happens to be close to 2.0. Objects strongly suspected of being stars
    on the basis of morphology and spectral energy distribution are not
    included in the masks as targets and are classified as "forbidden".
    These are about 15% of the I<22.5 sample. However, the criteria for
    this exclusion are deliberately quite conservative and about 4% of the
    spectroscopic targets turn out to be stars.

    For each slit there is a primary target. Naturally, sometimes other
    targets happen to fall in the same slit. These "secondary targets" are
    indicated by preceding the redshift confidence class (see below) by a
    "2". Sometimes, these secondary objects were forbidden, but their
    spectra were anyway reduced and included in the catalogue.

    Given the inevitable complexity of the sample, users who require
    statistically complete samples are strongly encouraged to contact the
    zCOSMOS team for guidance.

Acknowledgements:
    All publications based on ESO archive data should carry the
    following acknowledgement:
      "Based on observations made with the European Southern Observatory
       telescopes obtained from the ESO/ST-ECF Science Archive Facility."

File Summary:
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 FileName   Lrecl  Records   Explanations
--------------------------------------------------------------------------------
ReadMe         80        .   This file
zcosmos.dat   110    10643   zCOSMOS_VIMOS_bright_DR2 catalog
cutouts/*       .    10622  *Cut-out images of the catalog (jpg)
sp-1d/*         .    10643  *FITS calibrated spectra
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Note on cutouts/*, sp-1d/*: files from ESO Public Archive at
     http://archive.eso.org/cms/eso-data/data-packages/zcosmos-data-release-dr2
     Data from ESO archive should be acknowledged, see the
     "Acknowledgements" section above
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See also:
           III/250 : The VIMOS VLT deep survey (VVDS-DEEP) (Le Fevre+ 2005)
    J/A+A/428/1043 : Redshifts from VIMOS VLT Deep Survey (Le Fevre+, 2004)
            II/284 : COSMOS Multi-Wavelength Photometry Catalog (Capak+, 2007)
    J/ApJS/172/46  : VLA-COSMOS survey. II. (Schinnerer+, 2007)

Byte-by-byte Description of file (#): zcosmos.dat
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   Bytes Format Units   Label     Explanations
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   3-  8  I6    ---     zCOSMOS   [700137/960004] zCOSMOS identification number
  11- 20  F10.6 deg     RAdeg     Right ascension in decimal degrees (J2000)
  23- 30  F8.6  deg     DEdeg     Declination in decimal degrees (J2000)
  33- 38  F6.4  ---     z         ?=9.9999 Redshift
  41- 45  F5.1  ---     CC        Confidence Class indicating reliability (1)
  48- 52  F5.2  mag     Imag      Selection magnitude F814W, in AB system
      57  I1    ---     Flag      [0/2] Selection flag (unexplained)
  59-110  A52   ---     FileName  Original Name of the spectrum fits file (2)
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Note (1): Confidence Class (CC) defined as 3 digits (ab.c).

   * Unit digit (b in ab.c) represents the confidence class:
     --------------------------------------------------------------------
     CC Description            Spectroscopic     Photo-z consistency
                                verification      within dz=0.08(1+z)
     --------------------------------------------------------------------
     4  Very secure redshift,
         beautiful redshift    >99.5%             97%
     3  Secure redshift        >99.5%             97%
     9  One line redshift      95%                84%-95%  (after
         (best guess)          (after correction) correction with photo-z)
     2  Probable redshift      92%                93%
     1  Insecure redshift      70%                72%
     0  Unidentified spectrum
     --------------------------------------------------------------------

   * the decimal (.c) represents the Spectroscopic/photometric consistency:
     --------------------------------------------------------------------
     .5   Spectroscopic redshift consistent within 0.08(1+z) of the
          photometric redshift, both for galaxies, stars and AGN.
     .4   No photometric redshift available, includes all spectroscopic
          AGN and stars
     .3   Special case for Class 18 and 9: Consistent with photo-z only
          after the redshift changed to the alternate redshift,
          a switch which is then applied
     .1   Spectroscopic and photometric redshifts are not consistent at
          the level of 0.08(1+z)
     --------------------------------------------------------------------

    * the tens (a in ab.c) is
      ---------------------------
      0       = Galaxies and stars
      1 (+10) = Broad line AGN
      2 (+20) = Secondary targets
      ---------------------------

Note (2): Spectra are available at
     http://archive.eso.org/cms/eso-data/data-packages/\
           zcosmos-data-release-dr2/index_html#retrieval
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History: Data copied at
  http://archive.eso.org/cms/eso-data/data-packages/zcosmos-data-release-dr2
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(End)                                      Patricia Vannier [CDS]    02-Feb-2009