J/A+AS/127/167 V,I CCD photometry of NGC 6528 (Richtler+ 1998)
V,I CCD photometry of metal-rich globular clusters: NGC 6528
Richtler T., Grebel E.K., Subramaniam A., Sagar S.
<Astron. Astrophys. Suppl. Ser. 127, 167 (1998)>
=1998A&AS..127..167R 1998A&AS..127..167R (SIMBAD/NED BibCode)
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:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table6 51 24999 Position and photometry of 24999 stars
in a field of view of 5.7'x5.7'
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
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
--------------------------------------------------------------------------------
Note (1): the pixel size is 0.332arcsec, North up, West right.
--------------------------------------------------------------------------------
Acknowledgements: Tom Richtler
(End) Patricia Bauer [CDS] 12-Jun-1997