J/A+A/331/70 JKVI photometry of NGC 6553 stars (Guarnieri+ 1998)
Infrared Array Photometry of Bulge Globular Clusters.
I. Combined ground based JK and HST VI Photometry of NGC 6553
Guarnieri M.D., Ortolani S., Montegriffo P., Renzini B., Barbuy B.,
Bica E., Moneti A.
<Astron. Astrophys. 331, 70 (1998)>
=1998A&A...331...70G 1998A&A...331...70G (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Stars, blue ; Photometry, infrared
Keywords: globular clusters: NGC 6553 - Galaxy: center - blue stragglers -
HR diagram
Abstract:
JK infrared photometry for the bulge globular cluster NGC 6553,
combined with high resolution visual VI observations are presented and
discussed in connection with the bulge metal rich population. The
infrared data were taken with IRAC2 at ESO 2.2m telescope while the
optical counterparts are from Hubble Space Telescope (HST). We find a
mean magnitude for the horizontal branch of VHB=16.92, and
KHB=12.42±0.01. Assuming a reddening of E(B-V)=0.7, the mean
distance modulus is (m-M)0=13.6 giving an heliocentric distance of
5.2Kpc. This distance is slightly higher than that previously
published by Ortolani et al. (1990A&A...236..362O 1990A&A...236..362O, hereafter OBB90).
The brightest giants have been detected at K∼6.5 and (V-K)=13.10
transforming to MK=-7.34 and (V-K)0=11.20, which are exceptionally
high values for a globular cluster. The metallicity has been found to
be consistent with previous values and an average of
[Fe/H]=-0.22±0.05 has been adopted. The helium abundance estimated
via the R' method yields Yp∼0.28±0.03.
Objects:
----------------------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------------------
18 09 15.6 -25 54 28 NGC 6553
----------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
appen.dat 41 1426 VIJK photometry of 1426 stars
--------------------------------------------------------------------------------
Byte-by-byte Description of file: appen.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- No [1/48688]+ Sequential number (1)
7- 11 F5.2 mag Vmag HST V magnitude
13- 17 F5.2 mag Imag HST I magnitude
19- 23 F5.2 mag Jmag IRAC2 J magnitude
25- 29 F5.2 mag Kmag IRAC2 K magnitude
31- 35 F5.1 pix Xpos HST X position (2)
37- 41 F5.1 pix Ypos HST Y position
--------------------------------------------------------------------------------
Note (1): No 1 to 2197 belong to the WFPC2 PC chip
20001 to 26240 to the WFPC2 chip#2
30001 to 39545 to the WFPC2 chip#3
40001 to 48688 to the WFPC2 chip#4
Note (2): X position transformed to the IRAC2 reference frame
--------------------------------------------------------------------------------
History: Prepared via OCR at CDS from the manuscript.
(End) Patricia Bauer [CDS] 09-Sep-1997