J/A+A/488/481       Time delays and H0 from WFI J2033-4723      (Vuissoz+, 2008)
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COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses
VII. Time delays and the Hubble constant from WFI J2033-4723.
    Vuissoz C., Courbin F., Sluse D., Meylan G., Chantry V., Eulaers E.,
    Morgan C., Eyler M.E., Kochanek C.S., Coles J., Saha P., Magain P.,
    Falco E.E.
   <Astron. Astrophys. 488, 481 (2008)>
   =2008A&A...488..481V
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ADC_Keywords: QSOs ; Gravitational lensing ; Photometry
Keywords: gravitational lensing - cosmology: cosmological parameters -
          quasars: individual: WFI J2033-4723

Abstract:
    Gravitationally lensed quasars can be used to map the mass
    distribution in lensing galaxies and to estimate the Hubble constant
    H0 by measuring the time delays between the quasar images. Here we
    report the measurement of two independent time delays in the quadruply
    imaged quasar WFI J2033-4723 (z=1.66). Our data consist of R-band
    images obtained with the Swiss 1.2m EULER telescope located at La
    Silla and with the 1.3m SMARTS telescope located at Cerro Tololo.
    The light curves have 218 independent epochs spanning 3 full years of
    monitoring between March 2004 and May 2007, with a mean temporal
    sampling of one observation every 4th day.
    We measure the time delays using three different techniques, and we
    obtain Dt(B-A)=35.5+/-1.4days (3.8%) and Dt(B-C)=62.6^+4.1^_-2.3_days
    (^+6.5%^_-3.7%_), where A is a composite of the close, merging image
    pair. After correcting for the time delays, we find R-band flux ratios
    of FA/FB=2.88+/-0.04, FA/FC=3.38+/-0.06, and FA1/FA2=1.37+/-0.05 with
    no evidence for microlensing variability over a time scale of three
    years. However, these flux ratios do not agree with those measured in
    the quasar emission lines, suggesting that longer term microlensing is
    present. Our estimate of H0 agrees with the concordance value:
    non-parametric modeling of the lensing galaxy predicts
    H0=67^+13^_-10_km/s/Mpc, while the Single Isothermal Sphere model
    yields H0=63^+7^_-3_km/s/Mpc (68% confidence level). More complex lens
    models using a composite de Vaucouleurs plus NFW galaxy mass profile
    show twisting of the mass isocontours in the lensing galaxy, as do the
    non-parametric models. As all models also require a significant
    external shear, this suggests that the lens is a member of the group
    of galaxies seen in field of view of WFI J2033-4723.

Description:
    Photometry of WFI J2033-4723, as in Fig. 3 of the paper. The first
    column gives the Julian date and corresponds to HJD days. The
    second column is the seeing, in arcsec. Column 3-8 display the
    photometric measurements of the quasar components A, B and C
    respectively, with the corresponding error bars. The last column
    finally provides the name of the telescope used for each measurement.

Objects:
    --------------------------------------------------------------------
       RA   (2000)   DE      Designation(s)
    --------------------------------------------------------------------
    20 33 42.1   -47 23 43   WFI J2033-4723 = [MCS2004b] WFI J2033-4723
    --------------------------------------------------------------------

File Summary:
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 FileName   Lrecl  Records   Explanations
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ReadMe         80        .   This file
table4.dat     58      218   Photometry of WFI J2033-4723, as in Fig.3 of paper
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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- 10  F10.2 d       HJD       Julian date
  12- 15  F4.2  arcsec  Seeing    Seeing
  17- 21  F5.3  mag     magA      Magnitude of quasar image A
  23- 27  F5.3  mag   e_magA      Magnitude error bar of quasar image A
  29- 33  F5.3  mag     magB      Magnitude of quasar image B
  35- 39  F5.3  mag   e_magB      Magnitude error bar of quasar image B
  41- 45  F5.3  mag     magC      Magnitude of quasar image C
  47- 51  F5.3  mag   e_magC      Magnitude error bar of quasar image C
  53- 58  A6    ---     Tel       Telescope used (EULER or SMARTS)
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Acknowledgements: Christel Vuissoz, christel.vuissoz(at)epfl.ch

References:
   Eigenbrod et al.,  Paper I     2005A&A...436...25E
   Eigenbrod et al.,  Paper II    2006A&A...451..747E
   Eigenbrod et al.,  Paper III   2006A&A...451..759E
   Saha et al.,       Paper IV    2006A&A...450..461S
   Vuissoz et al.,    Paper V     2007A&A...464..845V
   Eigenbrod et al.,  Paper VI    2007A&A...465...51E

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(End)  Christel Vuissoz [EPFL, Switzerland], Patricia Vannier [CDS]  11-Aug-2008
