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J/A+AS/127/167      V,I CCD photometry of NGC 6528 (Richtler+ 1998)
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V,I CCD photometry of metal-rich globular clusters: NGC 6528
       Richtler T., Grebel E.K., Subramaniam A., Sagar R.
      <Astron. Astrophys. Suppl. Ser. 127, 167 (1998)>
      =1998A&AS..127..167R      (SIMBAD/NED BibCode)
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ADC_Keywords: Clusters, globular ; Photometry, CCD
Keywords: Galaxy: globular clusters: general; individual: NGC 6528 -
          Galaxy: abundances - HR diagram

Abstract:
    We present CCD photometry in V and I for the metal-rich globular
    cluster NGC 6528. A comparison with previous photometry reveals
    discrepancies of the order 0.1 to 0.2mag in V, emphasizing the need
    for independent photometry. As found previously, the giant branch (or
    the asymptotic giant branch, which cannot be distinguished) of the
    cluster extends to V-I=7. Population synthesis in V-I must take
    these red stars into account in order to understand integrated red
    colours of bulge populations. Currently available theoretical
    isochrones do not reproduce the shape of the RGB/AGB. The derivation
    of reliable values for reddening, distance and metallicity of NGC 6528
    is hampered by uncertainties in the extrapolation to high metallicity,
    which dominate the absolute error rather than the photo metric
    uncertainty does. Together with other properties (old age derived from
    HST data, high radial velocity), this object is more likely a member
    of the bulge than of the disk population.

Objects:
    ----------------------------------------------------------
        RA   (2000)   DE     Designation(s)
    ----------------------------------------------------------
    18 04 49.5   -30 03 21   NGC 6528
    ----------------------------------------------------------

File Summary:
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  FileName        Lrecl  Records   Explanations
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ReadMe             80        .   This file
table6             51    24999   Position and photometry of 24999 stars
                                  in a field of view of 5.7'x5.7'
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Byte-by-byte Description of file: table6
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   Bytes Format Units   Label     Explanations
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   1-  5  I5    ---     Seq       Sequential number
   7- 13  F7.2  pix     Xpos      X position (1)
  15- 21  F7.2  pix     ypos      Y position (1)
  23- 28  F6.3  mag     Vmag      V magnitude
  30- 34  F5.3  mag   e_Vmag      rms uncertainty on Vmag
  36- 40  F5.3  mag     V-I       V-I colour index
  42- 46  F5.3  mag   e_V-I       rms uncertainty on V-I
  48- 51  F4.1  ---     Chi       chi-value returned from DAOPHOT
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Note (1): the pixel size is 0.332arcsec, North up, West right.
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Acknowledgements: Tom Richtler <richtler@astro.uni-bonn.de>
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(End)                                         Patricia Bauer [CDS]   12-Jun-1997