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J/AJ/116/2081   Hubble Deep Field catalog of color-based redshift  (Wang+, 1998)
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A catalog of color-based redshift estimates for z<~4 galaxies in the
Hubble Deep Field.
       Wang Y., Bahcall N., Turner E.L.
      <Astron. J. 116, 2081 (1998)>
      =1998AJ....116.2081W      (SIMBAD/NED BibCode)
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ADC_Keywords: Galaxies, photometry ; Redshifts ; Photometry, UBVRI
Mission_Name: HST
Keywords: galaxies: distances and redshifts - methods: data analysis

Abstract:
    We derive simple empirical color-redshift relations for z<~4 galaxies
    in the Hubble Deep Field (HDF) using a linear function of three
    photometric colors (U-B, B-V, V-I). The dispersion between the
    estimated redshifts and the spectroscopically observed ones is small
    for relations derived in several separate color regimes; the
    dispersions range from {sigma}_z_~=0.03 to 0.1 for z<~2 galaxies, and
    from {sigma}_z_~=0.14 to 0.25 for z>~2 galaxies. We apply the
    color-redshift relations to the HDF photometric catalog and obtain
    estimated redshifts that are consistent with those derived from
    spectral template fitting methods. The advantage of these
    color-redshift relations is that they are simple and easy to use and
    do not depend on the assumption of any particular spectral templates;
    they provide model independent redshift estimates for z<~4 galaxies
    using only multiband photometry, and they apply to about 90% of all
    galaxies. We provide a color-based estimated redshift catalog of HDF
    galaxies to z<~4. We use the estimated redshifts to investigate the
    redshift distribution of galaxies in the HDF; we find peaks in the
    redshift distribution that suggest large-scale clustering of galaxies
    to at least z~1 and that are consistent with those identified in
    spectroscopic probes of the HDF.

File Summary:
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  FileName      Lrecl  Records   Explanations
--------------------------------------------------------------------------------
ReadMe             80        .   This file
table2.dat         66      848   Catalog of color-based redshift estimates
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See also:
  J/A+AS/129/583 : Hubble Deep Field surface photometry (Fasano+ 1998)
   J/AJ/112/1335 : Hubble Deep Field observations (Williams+ 1996)
    J/AJ/112/359 : Galaxies in the Hubble Deep Field (van den Bergh+ 1996)
    J/ApJ/471/L5 : Redshift clustering in the Hubble Deep Field (Cohen+ 1996)

Table 1: galaxies not used in determining the z_a_ relations
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 Sawicki   x       y      z     za   ztemp
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  20288 1831.00  753.00 0.609 0.9100 0.65
  20456  527.00 1096.00 0.390 0.9474 1.10
  30096  716.91  451.61 0.089 0.2757 2.00
  30111 1463.00  489.00 1.315 0.9444 1.05
  30251 1040.70  774.70 0.642 0.8456 0.70
  30802 1618.80 1926.50 0.472 0.7770 0.85
  40224 1961.00  599.00 0.961 0.7631 0.95
  40818 1002.50 1771.70 0.882 1.5494 2.25
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 Sawicki: From Sawicki et al. (1997AJ....113....1S)catalog,
           1st number is chip number
    x, y: pixel position on v.2 HDF images
       z: spectroscopic redshift
      za: color-based redshift
   ztemp: redshift from spectral template-fitting
---------------------------------------------------------------

Byte-by-byte Description of file: table2.dat
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   Bytes Format Units  Label   Explanations
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   1-  5  I5    ---    Sawicki Identification number in Sawicki et al.
                                (1997AJ....113....1S) photometric catalog (1)
   7- 13  F7.2  pix    xpos    x position on v2 HDF image
  15- 21  F7.2  pix    ypos    y position on v2 HDF image
  23- 27  F5.2  mag    m814    m814 (I) magnitude
  29- 33  F5.2  mag    m606    m606 (V) magnitude
  35- 39  F5.2  mag    m450    m450 (B) magnitude
  41- 45  F5.2  mag    m300    m300 (U) magnitude
  47- 50  F4.2  ---    ztemp   Photometric redshift from fitting spectral
                               templates by Sawicki et al. (1997AJ....113....1S)
  52- 56  F5.2  ---    za      Color-based analytic redshift
      57  A1    ---    Note    [*] Note (2)
      59  I1    ---    cr      Color range
  61- 65  F5.3  ---    z       ? Spectroscopic redshift
      66  A1    ---  u_z       [?] Uncertainty flag on z (3)
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Note (1): First digit is chip number
Note (2): * indicates the 83 galaxies for which |za-ztemp|> 0.5; 4 of these
           have spectroscopic redshifts z, and |za-z| is much smaller than
           |ztemp-z|; about half of the 83 galaxies lie close to the border
           of |za-ztemp|<=0.5.
Note (3): ? indicates the three galaxies for which the reported spectroscopic
             redshifts are erroneous or very uncertain.
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History: Copied at ftp://astro.princeton.edu/elt/:HDF
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(End)                           James Marcout, Patricia Bauer [CDS]  19-Jan-1999