J/A+AS/145/365      BVI photometry of NGC 7790               (Gupta+, 2000)
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A complete photometric study of the open cluster NGC 7790 containing
Cepheid variables.
     Gupta A.C., Subramaniam A., Sagar R., Griffiths W.K.
    <Astron. Astrophys. Suppl. Ser. 145, 365 (2000)>
    =2000A&AS..145..365G
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ADC_Keywords: Clusters, open ; Photometry, CCD ; Photometry, Cousins
Keywords: Galaxy: open clusters: individual: NGC 7790 - stars: evolution -
          HR diagram

Abstract:
    CCD photometry of the northern open star cluster NGC 7790 has been
    carried out in BVI photometric passbands down to V~21mag for 1150
    stars of which for ~700 stars, the data is obtained for the first
    time. We derive the most reliable parameters for this cluster using
    all the available photometric, spectroscopic and proper motion data.
    The interstellar extinction over the cluster area is uniform and
    normal with E(B-V)=0.51+/-0.03mag. We determine a distance of
    3.3+/-0.23Kpc to the cluster. The theoretical isochrone fittings to
    the Cepheid variables as well as the evolved part of the main-sequence
    near turn-off point indicate that the cluster is 120+/-20Myr old. We
    estimate the cluster radius to be 3.7' using radial stellar density
    profile. Both the distance and age determined using period
    luminosity/age relations for the Cepheid variables are consistent
    with their membership of the cluster. This unique opportunity has
    therefore been used to refine the zero-point of the period-luminosity
    relation for the Galactic Cepheids.

Objects:
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       RA   (2000)   DE      Designation(s)
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    23 58 24     +61 13.0    NGC 7790 = C 2355+609
    ------------------------------------------------

File Summary:
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 FileName      Lrecl  Records   Explanations
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ReadMe            80        .   This file
table1.dat        67     1156   Relative (X, Y) pixel positions and CCD BVI
                                magnitudes of stars measured in the field of
                                NGC 7790 are presented.
table1.tex        82     1272   LaTeX version of table 1
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See also:
           V/28 : Proper motions and UBV phot. in 4 open clusters (Frolov 1980)
 J/PASP/104/553 : CCD Standard Fields (Odewahn+ 1992)

Byte-by-byte Description of file: table1.dat
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   Bytes Format Units   Label     Explanations
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   2-  5  I4    ---     Seq       Sequential number (1)
   7- 12  F6.2  pix     Xpos      X position (2)
  14- 19  F6.2  pix     Ypos      Y position (2)
  21- 26  F6.3  mag     Vmag      V magnitude
  28- 33  F6.3  mag     B-V       ? B-V colour index
  35- 40  F6.3  mag     V-I       V-I Cousins colour index
  42- 68  A27   ---     Names     Other identifications, separated by commas (3)
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Note (1): Numbers are the same as Phelps & Janes (1994ApJS...90...31P)
          Numbers staring from 5001 is new detection of stars in this cluster
Note (2): The coordinate system is that of the database given by Phelps & Janes
           (1994ApJS...90...31P). The center of the cluster is located at
            RA = 23h 54min 12s, DE = +60{deg} 57' (1950.0)
           1 pix = 0.74". North is up, and east is to the left.
Note (3): Other identifications:
       F: Frolov, 1977IzPul.195...80F, Cat. <V/28>
       I: Iyeshima et al., 1994, Ann. Rep. Nishi - Harima Astron. Obs. 4, 18
       O: Odewahn et al., 1992PASP..104..553O, Cat. <J/PASP/104/553>
       P: Pedreros et al., 1984ApJ...286..563P
       R: Romeo et al., 1989MNRAS.240..459R
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Acknowledgements: Alok Chandra Gupta <acgupta@prl.ernet.in>
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(End)                                        Patricia Bauer [CDS]    05-Dec-2000
