J/AJ/119/1760 M54 and Sgr dSph VI photometry (Layden+, 2000)
Photometry of the globular cluster M54 and the Sagittarius Dwarf Galaxy:
the age-metallicity relation.
Layden A.C., Sarajedini A.
<Astron. J. 119, 1760 (2000)>
=2000AJ....119.1760L 2000AJ....119.1760L
ADC_Keywords: Clusters, globular ; Galaxies, photometry ; Stars, variable
Keywords: galaxies: individual (Sagittarius) - galaxies: star clusters -
galaxies: stellar content - globular clusters: individual (M54) -
stars: variables: general
Abstract:
We present deep VI-band photometry of the globular cluster M54, a
nearby field in the Sagittarius dwarf galaxy, and a control field. The
color-magnitude diagrams reach well below the oldest main-sequence
turnoffs, thus enabling an analysis of the galaxy's age-metallicity
relation with unprecedented clarity. We also study the variable stars
in the direction of M54. From 67 RR Lyrae variables, we confirm and
improve on our previous estimates of the cluster horizontal branch
magnitude, foreground reddening, and horizontal branch morphology.
These values are used in determining the ages of M54 and the
Sagittarius field populations. We confirm our previous result that M54
is the same age as Galactic globular clusters of similar metallicity.
Objects:
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RA (2000) DE Designation(s)
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18 55 03.3 -30 28 43 M 54 = NGC 6715
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 52 20342 Photometry of M54 from shallow frames
table3.dat 52 30081 Photometry of M54 from deep frames
table4.dat 52 1638 Photometry of Sagittarius from shallow frames
table5.dat 52 10147 Photometry of Sagittarius from deep frames
table6.dat 52 7917 Photometry of the control field
table8.dat 47 14 Mean photometry of suspected variable stars
table9.dat 104 71 Photometric properties of short-period
variable stars
table10.dat 62 18 Mean photometry of long-period variable stars
table11.dat 43 4 Mean photometry of faint variable stars
notes.dat 80 90 Individual notes of table9.dat
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See also:
J/AJ/109/1086 : VI Photometry in M54 and Sgr Dwarf Galaxy (Sarajedini+ 1995)
Byte-by-byte Description of file: table[2-6].dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- ID Identification number (1)
7- 13 F7.2 pix Xpos X position (2)
15- 21 F7.2 pix Ypos Y position (2)
23- 28 F6.3 mag Vmag V magnitude
31- 35 F5.3 mag e_Vmag rms uncertainty on Vmag
37- 42 F6.3 mag Imag I magnitude
45- 49 F5.3 mag e_Imag rms uncertainty on Vmag
52 I1 --- Nobs Number of observations
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Note (1): Simbad designations:
Table 2: <Cl* NGC 6715 LSSF NNNNN> N=20342
Table 3: <Cl* NGC 6715 LSDF NNNNN> N=30081
Table 4: [SL95] Sgr NNNN, N=1638
Table 5: <[LS2000] Sgr NNNNN> N=10147
Table 6: <[LS2000] BCF NNNN> N=7917
Note (2): North is to the right, and east is up. 1 pix = 0.43"
For M54, coordinates are from fig. 1 with (X, Y)=(1, 1) at the lower
left and (1551, 1551) at the upper right. The cluster center is at
(X, Y) = (726, 806) pixels. In Simbad, M54 is at RA=18h55min03.28s,
DE=-30°28'42.6" (J2000).
For Sagitarius, coordinates are from fig. 3 with (X, Y) = (1, 1) at
the lower left and (1150, 1150) at the upper right. In Simbad,
Sagitarius dwarf galaxy is at RA=18h55.1min, DE=-30°29' (J2000)
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Byte-by-byte Description of file: table8.dat table10.dat table11.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Var Variable Star designation (1)
6- 11 F6.1 pix Xpos X position (G1)
13- 18 F6.1 pix Ypos Y position (G1)
20- 24 F5.2 mag <Vmag> Mean V magnitude
26- 29 F4.2 mag <V-I> Mean V-I colour index
31- 34 F4.2 mag DVmag Amplitude in V magnitude
36- 62 A27 --- Com Comments
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Note (1): Simbad designations:
SVN: <Cl* NGC 6715 LSS VN> (Nos SV1-SV3).
VNNN: <Cl* NGC 6715 Saw VNNN> (Nos V83-V117)
SgrN: <[LS2000] Sgr VN>
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Byte-by-byte Description of file: table9.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- Var Variable star designation
<Cl* NGC 6715 Saw VNNN> in Simbad
6- 11 F6.1 pix Xpos X position (G1)
13- 18 F6.1 pix Ypos Y position (G1)
20- 26 F7.5 d Per Period
28- 32 A5 --- Type Variablity type
34- 39 F6.3 mag <Vmag> Intensity-mean V magnitude
41- 46 F6.3 mag <Imag> ?=99.999 Intensity-mean I magnitude
48- 53 F6.3 mag Vmax Maximum V magnitude
55- 60 F6.3 mag Vmin Minimum V magnitude
62- 74 F13.5 d Emax Epoch of maximum light (JD)
76- 77 I2 --- Nobs Number of observations in V frame
79- 80 I2 --- Ntmp Template number used in the adopted fit
82- 86 F5.3 mag rms root-mean-squared scatter of the data points
about the fit
88- 92 F5.3 mag (V-I)min Magnitude-mean (V-I) colour at minimum light
94- 99 F6.3 mag e_(V-I)min ?=99.999 rms uncertainty on (V-I)min
101-102 I2 --- Nmin Number of observations used in its computation
104 A1 --- Note [*] Note detailed in notes.dat file
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Byte-by-byte Description of file: notes.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Var Variable star designation
6- 80 A75 --- Note Text of the note
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Global Notes:
Note (G1): Coordonates in M54:
North is to the right, and east is up. 1 pix = 0.43".
Coordinates are from fig. 1 with (X, Y)=(1, 1) at the lower left and
(1551, 1551) at the upper right.
The cluster center (M54) is at (X, Y)=(726, 806) pixels.
History: From AJ electronic version
(End) James Marcout, Patricia Bauer [CDS] 02-May-2000