J/AJ/107/230 BVRI CCD photometry of NGC 1904 (Alcaino+, 1994)
BVRI CCD photometry of the globular cluster NGC 1904 (M79)
ALCAINO G., LILLER W., ALVARADO F., WENDEROTH E.
<Astron. J. 107, 230 (1994)>
=1994AJ....107..230A 1994AJ....107..230A (SIMBAD/NED Reference)
ADC_Keywords: Clusters, globular; Photometry, CCD; Positional data
Abstract:
We present BVRI photometry of three overlapping fields in the globular
cluster NGC 1904 (M79), observed with a CCD camera and the 2.2m
Max-Planck-Institute telescope at ESO/La Silla. We critically compare
our photometry using the INVENTORY data reduction code with results
derived by other investigators using different codes. These
comparisons convince us that all modern codes give results reliable to
at least ±0.3mag at all levels, as long as the fields are not
overly crowded. Specifically, our results for NGC 1904 (M79) are as
follows: V(TO)=19.60±0.10 (estimated external error), with
turnoff colors at B-V=0.40, V-R=0.27, V-I=0.57, and B-I=0.97,
all with estimated external errors of ±0.06. By fitting the four
resulting ridge lines to the theoretical isochrones of VandenBerg &
Bell [ApJS, 58, 561 (1985)] interpolated to [Fe/H]=-1.60, Y=0.20,
and [O/Fe]=0.00, we derive an average value for the age of 16Gyr,
where we have adopted E(B-V)=0.01.
Addresses: Instituto Isaac Newton, Ministerio de Educacion de Chile,
Casilla 8-9, Correo 9, Santiago, Chile
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table6.dat 69 750 CCD coordinates, magnitudes, and colors for
750 stars in NGC 1904
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Byte-per-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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2- 4 I3 --- Star Star number
5- 6 A2 --- n_Star Additional note for Star (1)
8- 12 F5.1 pix X X CCD coordinate
16- 20 F5.1 pix Y Y CCD coordinate
24- 29 F6.3 mag Vmag V magnitude
33- 37 F5.3 mag B-V []? B-V color
41- 45 F5.3 mag V-R []? V-R color
49- 53 F5.3 mag R-I []? R-I color
57- 61 F5.3 mag V-I []? V-I color
65- 69 F5.3 mag B-I []? B-I color
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Note (1): Two variables reported by Sawyer-Hogg (1973, Pub. David Dunlop Obs.
(University of Toronto Press, Toronto), Vol. 3, No. 6) lie in the
observed area, and are marked "V2" (Star 437) and "V4" (Star 470).
Also, the 6 standard stars are labelled "B" (Star 311), "C" (Star
714), "D" (Star 385), "E" (Star 303), "F" (Star 289), and "G" (Star
405). Table 4 of the printed paper details the observations of the
standards.
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Origin: AAS CD-ROM series, Volume 2, 1994
(End) Lee Brotzman [ADS] 21-May-1994, Patricia Bauer [CDS] 19-Oct-1994