J/AJ/119/2274 JK Photometry of globular clusters M15 & M56 (Ivanov+, 2000)
Extending the red giant branch versus metallicity calibration toward
metal-poor systems: near-infrared photometry of the galactic globular clusters
M56 and M15
Ivanov V.D., Borissova J., Alonso-Herrero A., Russeva T.
<Astron. J. 119, 2274 (2000)>
=2000AJ....119.2274I 2000AJ....119.2274I
ADC_Keywords: Clusters, globular ; HR diagrams ; Photometry, infrared
Keywords: color-magnitude diagrams - globular clusters: individual (Liller 1,
M15, M56, NGC 6553, NGC 7099) - stars: Population II
Abstract:
Infrared JKs-band photometry of the Galactic globular clusters M15
and, for the first time, M56 is presented. We estimate the reddening
[E(B-V) = 0.18 {=/-} 0.08 mag] and distance modulus [(m - M)V =
15.43 ± 0.30 mag] toward the poorly studied globular cluster M56.
We combine our data with observations of other clusters from the
literature (12 in total) to extend the [Fe/H] versus red giant branch
(RGB) slope relation toward metal-poor clusters.
Description:
We obtained JKs imaging of M56 and M15 using a 256 X 256 NICMOS3
array at the 2.3 m Bok Telescope of the University of Arizona on Kitt
Peak, with a plate scale of 0.6" pixel-1, under photometric conditions
on 1998 November 5. The average seeing during the observations was
1.0" - 1.2". The observational strategy consisted of taking cluster
images interleaved with sky images 6' - 7' away from the targets.
Objects:
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RA (2000) DE Designation(s)
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21 29 58.4 +12 10 01 M15 = NGC 7078
19 16 35.5 +30 11 04 M56 = NGC 6779
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 58 1459 Photometry of globular clusters M15 and M56
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See also:
J/A+A/303/468 : Spectrospcopy, IR-photom. in globular clusters (Minniti, 1995)
J/A+A/331/70 : JKVI photometry of NGC 6553 stars (Guarnieri+ 1998)
J/AJ/109/1131 : JHK Photometry in Metal Rich Globulars. (Kuchinski+ 1995)
J/AJ/110/2844 : JHK photometry of globular clusters. III. (Kuchinski+ 1995)
J/AJ/109/1154 : JHK Photometry of Liller 1 (Frogel+ 1995)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Cluster Cluster name
6- 10 I5 --- Number Object number in Cluster (1)
13- 18 F6.2 pix Xpix CCD X coordinate relative to cluster center
21- 26 F6.2 pix Ypix CCD Y coordinate relative to cluster center
30- 34 F5.2 mag Kmag The Ks filter magnitude
(Persson et al. 1998AJ....116.2475P 1998AJ....116.2475P)
38- 42 F5.2 mag (J-K) The (J-Ks) color
46- 50 F5.2 mag e_Kmag DAOPHOT errors for Kmag
54- 58 F5.2 mag EJMag DAOPHOT errors for the J filter
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Note (1): Numbers larger than 10,000 are composed of the numbers from
Clement 2000 plus 10,000 for cross-identification.
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History:
From AJ electronic edition.
References:
Clement, C. M. 2000, in preparation
(End) Greg Schwarz [AAS] 23-May-2000