J/A+AS/86/209 UBVRI photometry in cluster Tr 18 (Vazquez+, 1990)
The open cluster Tr 18.
Vazquez R.A., Feinstein A.
<Astron. Astrophys. Suppl. Ser., 86, 209 (1990)>
=1990A&AS...86..209V 1990A&AS...86..209V
ADC_Keywords: Clusters, open ; Photometry, UBVRI
Keywords: open cluster ; UBVRI photometry ; stars: Cepheid.
Abstract: UBVRI photoelectric photometry was obtained in the field of
the open cluster Tr 18. From the analysis of the data we confirm
that several distant OB stars were wrongly assumed as cluster
members in previous investigations. The true distance modulus is
10.95, equivalent to a distance of 1550pc with the adopted age of
(9.0±1.0)x107yr. The GH Car Cepheid variable is very much probably
a cluster member in view of its spatial position and the average
absolute magnitude. However, some arguments are given to suggest
that the reality of this cluster is still an open question.
The observations in the Cousins system were carried out during 9
nights in April 1989 at Cerro Tololo Interamerican Observatory, with
a single channel photometer attaéched to the 60cm Lowell telescope.
The positions and identifications with large astrometric surveys
was achieved by B. Skiff (Lowell Obs.) in 2010.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 128 66 UBVRI photometry and positions of stars
in the field of Tr 18
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- --- [Cl* Trumpler 18 VF]
20- 22 I3 --- Seq [1,109] Sequential number of star in cluster
26- 27 I2 h RAh Right Ascension J2000 (hours) (1)
29- 30 I2 min RAm Right Ascension J2000 (minutes) (1)
32- 36 F5.2 s RAs Right Ascension J2000 (seconds) (1)
38 A1 --- DE- Declination J2000 (sign) (1)
39- 40 I2 deg DEd Declination J2000 (degrees) (1)
42- 43 I2 arcmin DEm Declination J2000 (minutes) (1)
45- 48 F4.1 arcsec DEs Declination J2000 (seconds) (1)
50 A1 --- s [UM] Reference of position: UCAC2 (I/289) (1)
or 2MASS (II/246) (1)
52- 59 I8 --- UCAC2 ? Number in UCAC2 catalog (I/289)
62- 66 F5.2 mag Vmag Johnson V magnitude
69- 73 F5.2 mag B-V Johnson (B-V) color index
76- 80 F5.2 mag U-B Johnson (U-B) color index
83- 87 F5.2 mag V-R Cousins (V-R) color index
90- 94 F5.2 mag V-I Cousins (V-I) color index
98-128 A31 --- Rem Remarks and cross-identifications (1)
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Note (1): added by B. Skiff in the 2010 version.
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(End) Brian Skiff [Lowell Obs.], Francois Ochsenbein [CDS] 10-Jan-2010