J/A+AS/122/9 CCD UBVRI Photometry of 4 open clusters (Sagar+ 1997)
Multicolour deep CCD photometric study of the moderately young southern open
star clusters NGC 3228, NGC 4103, NGC 5662 and NGC 6087
Sagar R., Cannon R.D.
<Astron. Astrophys. Suppl. Ser. 122, 9 (1997)>
=1997A&AS..122....9S 1997A&AS..122....9S
ADC_Keywords: Clusters, open ; Photometry, UBVRI
Keywords: HR diagram - stars: evolution -
open clusters and associations: individual: NGC 3228, NGC 4103,
NGC 5662, NGC 6087
Abstract:
CCD observations in the U, B, V, R and I passbands have been used to
generate colour-colour and deep colour-magnitude diagrams for the
young open star clusters NGC 3228, NGC 4103, NGC 5662 and NGC 6087.
The sample consists of about 2000 stars reaching down to V=20mag. The
interstellar extinction across the face of the imaged cluster regions
seems to be uniform with average values of E(B-V)=0.31, 0.34 and
0.22mag for NGC 4103, NGC 5662 and NGC 6087 respectively. The
distances to the clusters NGC 3228, NGC 4103, NGC 5662 and NGC 6087
have been estimated as 0.5±0.05, 2.0±0.3, 0.8±0.1 and
1.0±0.1kpc respectively, while the corresponding ages estimated from
the theoretical stellar evolutionary isochrones fitted to the bright
proper motion cluster members are ∼100, 30, 80 and 65Myr respectively.
Present data are consistent with the membership of the Cepheid
variable V Cen to NGC 5662 and of S Norm to NGC 6087. Heavy
contamination by foreground and background field stars has
unfortunately made it impossible to reach definite conclusions about
the faint luminosity function, and the data do not reach faint enough
limits to investigate pre-main sequence stars.
Description;
The observations in UBV Johnson and RI Kron-Cousins passbands were
carried out between 27March-02April and 22-28June 1989 on the ANU 1.0m
telescope at Siding Spring Observatory, using a blue coated GEC P8603
CCD in an Astromed camera system mounted at the f/8 Cassegrain focus;
the scale is 0.56arcsec/pix, and the brightness range is 8.8-16.5mag
in V. During the observations typical seeing was 1.5arcsec.
Objects:
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RA (2000) DE Designation(s)
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10 21.8 -51 43 NGC 3228 = C 1019-514
12 06.7 -61 15 NGC 4103 = C 1204-609
14 35.2 -56 33 NGC 5662 = C 1431-563
16 18.9 -57 54 NGC 6087 = C 1614-577
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table6.dat 55 408 Relative positions and UBVRI mag in NGC 3228
table7.dat 62 288 Relative positions and UBVRI mag in NGC 4103
table8.dat 80 502 Relative positions and UBVRI mag in NGC 5662
table9a.dat 56 418 Relative positions and UBVI mag in Region 1 of
NGC 6087
table9b.dat 63 381 Relative positions and UBVRI mag in Regions 2
and 3 of NGC 6087
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Byte-by-byte Description of file: table6.dat table7.dat table8.dat table9b.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
2- 4 I3 --- Seq Sequential star number
5- 12 F8.2 pix Xpos X position
13- 20 F8.2 pix Ypos Y position
21- 27 F7.2 mag Vmag V Johnson magnitude
28- 34 F7.2 mag U-B ? U-B Johnson colour index
35- 41 F7.2 mag B-V ? B-V Johnson colour index
42- 48 F7.2 mag V-R ? V-R Kron-Cousins colour index
49- 55 F7.2 mag V-I ? V-I Kron-Cousins colour index
56- 80 A25 --- Name Other identifications (1)
--------------------------------------------------------------------------------
Note (1): Prefixes used:
W = Wesselink, 1969MNRAS.146..329W 1969MNRAS.146..329W
MV = Moffat & Vogt, 1973A&AS...10..135M 1973A&AS...10..135M
H = Haug, 1978A&AS...34..417H 1978A&AS...34..417H
K = King, 1980, J. Proc. R. Soc. N.S.W. 113, 7
C = Claria et al., 1991MNRAS.249..193C 1991MNRAS.249..193C
L = Landoldt, 1964ApJS....8..329L 1964ApJS....8..329L
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Byte-by-byte Description of file: table9a.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
2- 4 I3 --- Seq Sequential star number
5- 12 F8.2 pix Xpos X position
13- 20 F8.2 pix Ypos Y position
21- 27 F7.2 mag Vmag V Johnson magnitude
28- 34 F7.2 mag U-B ? U-B Johnson colour index
35- 41 F7.2 mag B-V ? B-V Johnson colour index
42- 48 F7.2 mag V-I V-I Kron-Cousins colour index
49- 80 A32 --- Name Other identifications (1)
--------------------------------------------------------------------------------
Note (1): L: Landoldt (1964ApJS....8..329L 1964ApJS....8..329L)
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Acknowledgements: Ram Sagar
References:
Claria et al. 1991, MNRAS 249, 193 =1991MNRAS.249..193C 1991MNRAS.249..193C
Haug 1978, A&AS 34, 417 =1978A&AS...34..417H 1978A&AS...34..417H
King 1980, J. Proc. R. Soc. N.S.W. 113, 7 (= Sydney Obs. Papers No. 87)
Landoldt 1964, ApJS 8, 329 =1964ApJS....8..329L 1964ApJS....8..329L
Moffat & Vogt 1973, A&AS 10, 135 =1973A&AS...10..135M 1973A&AS...10..135M
Wesselink 1969, MNRAS 146, 329 =1969MNRAS.146..329W 1969MNRAS.146..329W
(End) Patricia Bauer [CDS] 24-Jul-1996