J/AJ/120/3111 Stromgren photometry of NGC 6397 (Anthony-Twarog+, 2000)
CCD uvbyHβ photometry in clusters.
II. The nearest globular cluster, NGC 6397.
Anthony-Twarog B.J., Twarog B.A.
<Astron. J., 120, 3111-3126 (2000)>
=2000AJ....120.3111A 2000AJ....120.3111A
ADC_Keywords: Clusters, globular ; Photometry, uvby, beta
Keywords: globular clusters: individual (NGC 6397) - techniques: photometric
Abstract:
CCD photometry extending below the turnoff of the globular cluster
NGC 6397 on the uvbyHβ system is presented and analyzed.
Restricting the sample to stars with small photometric errors and
highly probable cluster membership, the reddening from approximately
1500 stars at the turnoff is E(b-y)=0.127±0.002 (standard error of
the mean), equivalent to E(B-V)=0.179±0.003. The photometric
abundance for the same sample, on the revised spectroscopic scale for
globular clusters, is [Fe/H]=-1.82±0.04 (standard error of the
mean). From 220 cluster red giants, well-defined relations are
established for m1 and c1 as a function of b-y.
Description:
Photoelectric photometry on the uvbyCa system of a modest sample of
brighter stars in NGC 6397 was obtained over a series of runs at Cerro
Tololo Inter-American Observatory between 1990 and 1992. The data were
collected within the context of a program to observe field halo giants
using traditional photometers on the 1.0m and 1.5m telescopes; the
data for NGC 6397 were obtained only with the 1.5m telescope.
Objects:
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RA (2000) DE Designation(s)
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17 40 41.4 -53 40 25 NGC 6397 = GCl 74
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 60 15 Photoelectric photometry in NGC 6397
table2.dat 105 5137 CCD Photometry in NGC 6397
table3.dat 79 50 Normal sequences for NGC 6397
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See also:
J/AJ/119/2282 : Stromgren photometry of IC 4651 (Anthony-Twarog+, 2000)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name Stellar identification (1)
9- 14 F6.3 mag Vmag ? V-band magnitude
16- 20 F5.3 mag e_Vmag ? uncertainty in Vmag
22- 26 F5.3 mag b-y ? b-y color index
28- 32 F5.3 mag e_b-y ? uncertainty in b-y
34 I1 --- Nyb ? Number of stars observed in y and b
36- 40 F5.3 mag m1 ? m1 metallicity-sensitive index
magnitude
42- 46 F5.3 mag e_m1 ? uncertainty in m1
48- 52 F5.3 mag c1 ? c1 band magnitude
54- 58 F5.3 mag e_c1 ? uncertainty in c1
60 I1 --- Nvu ? Number of stars observed in u and v
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Note (1): Reference for the stars:
Alc = Alcaino 1977A&AS...29..397A 1977A&AS...29..397A, Cl* NGC 6397 ALC NNN
ROB = Woolley et al. 1961RGOB...43..303W 1961RGOB...43..303W, NGC 6397 NNNN
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name Stellar identification (1)
9- 14 F6.1 pix Xpos X position on the CCD
16- 21 F6.1 pix Ypos Y position on the CCD
23- 28 F6.3 mag Vmag V-band magnitude
31- 35 F5.3 mag b-y b-y color index
37- 42 F6.3 mag m1 m1 metallicity-sensitive index magnitude
44- 49 F6.3 mag c1 c1-band magnitude
51- 57 F7.3 mag beta Hβ-band magnitude
59- 63 F5.3 mag e_Vmag uncertainty in Vmag
65- 69 F5.3 mag e_b-y uncertainty in b-y
71- 75 F5.3 mag e_m1 uncertainty in m1mag
77- 81 F5.3 mag e_c1 uncertainty in C1mag
83- 87 F5.3 mag e_beta uncertainty in beta
89- 90 I2 --- Ny Number of stars observed in y
92- 93 I2 --- Nb Number of stars observed in b
95- 96 I2 --- Nv Number of stars observed in v
98- 99 I2 --- Nu Number of stars observed in u
101-102 I2 --- Nw Number of stars observed in β-wide
104-105 I2 --- Nn Number of stars observed in β-narrow
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Note (1): Reference for the star names:
Alc = Alcaino, 1977A&AS...29..397A 1977A&AS...29..397A, Cl* NGC 6397 ALC
ROB = Woolley et al., 1961RGOB...43..303W 1961RGOB...43..303W, NGC 6397 NNNN
A&L = Alcaino & Liller, 1980AJ.....85..680A 1980AJ.....85..680A, Cl* NGC 6397 AL
R&B = Rubenstein & Bailyn, 1996AJ....111..260R 1996AJ....111..260R
V = Kaluzny, 1997A&AS..122....1K 1997A&AS..122....1K, Cl* NGC 6397 SAW VNN
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Type Stellar type (Giants, AGB or BHB)
8- 13 F6.3 mag Vmag V-band magnitude
15- 19 F5.3 mag e_Vmag ? uncertainty in Vmag
21- 25 F5.3 mag b-y b-y color index
27- 31 F5.3 mag e_b-y ? uncertainty in b-y
33- 37 F5.3 mag m1 m1 metallicity-sensitive index magnitude
39- 43 F5.3 mag e_m1 ? uncertainty in m1
45- 47 I3 --- Nybv ? Number of stars observed in y, b and v
49- 53 F5.3 mag c1 c1-band magnitude
55- 59 F5.3 mag e_c1 ? uncertainty in c1
61- 63 I3 --- Nu ? Number of stars observed in u
65- 69 F5.3 mag beta Hβ-band magnitude
71- 75 F5.3 mag e_beta ? uncertainty in beta
77- 79 I3 --- Nbeta ? Number of stars observed in β
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History:
From electronic version of the journal
References:
Anthony-Twarog & Twarog, Paper I 2000AJ....119.2282A 2000AJ....119.2282A, Cat. J/AJ/119/2282
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 27-May-2010