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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      (SIMBAD/NED BibCode)
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.
Objects:
    ------------------------------------------
         RA (2000) DE    Designation(s)
    ------------------------------------------
      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
    ------------------------------------------

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table6            80      408   Relative positions and UBVRI mag in NGC 3228
table7            80      288   Relative positions and UBVRI mag in NGC 4103
table8            80      502   Relative positions and UBVRI mag in NGC 5662
table9a           80      418   Relative positions and UBVRI mag in
                                  Region 1 of NGC 6087
table9b           80      381   Relative positions and UBVRI mag in
                                  Regions 2 and 3 of NGC 6087


Byte-by-byte Description of file: table6 table7 table8 table9b

   Bytes Format  Units   Label    Explanations

   2-  4  I3     ---     SeqNum   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 magnitude
  28- 34  F7.2   mag     U-B      ? U-B colour index
  35- 41  F7.2   mag     B-V      ? B-V colour index
  42- 48  F7.2   mag     V-R      ? V-R colour index
  49- 55  F7.2   mag     V-I      ? V-I colour index
  56- 80  A25    ---     Name     Other identifications (1)

Note (1):  Prefixes are:
           W: Wesselink, 1969MNRAS.146..329W
          MV: Moffat & Vogt, 1973A&AS...10..135M
           H: Haug, 1978A&AS...34..417H
           K: King, 1980, J. Proc. R. Soc. N.S.W. 113, 7
           C: Claria et al., 1991MNRAS.249..193C
           L: Landoldt, 1964ApJS....8..329L


Byte-by-byte Description of file: table9a

   Bytes Format  Units   Label    Explanations

   2-  4  I3     ---     SeqNum   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 magnitude
  28- 34  F7.2   mag     U-B      ? U-B colour index
  35- 41  F7.2   mag     B-V      ? B-V colour index
  42- 48  F7.2   mag     V-I      V-I colour index
  49- 80  A32    ---     Name     Other identifications (1)

Note (1): L: Landoldt (1964ApJS....8..329L)



Acknowledgements: Ram Sagar 


References:
   Claria et al. 1991, MNRAS 249, 193 =1991MNRAS.249..193C
   Haug 1978, A&AS 34, 417            =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
   Moffat & Vogt 1973, A&AS 10, 135   =1973A&AS...10..135M
   Wesselink 1969, MNRAS 146, 329     =1969MNRAS.146..329W
(End)                                        Patricia Bauer  [CDS]   24-Jul-1996