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J/A+AS/118/503      Proper motions of stars in Ori Nebula (Tian+ 1996)
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Proper motions of stars in the region of the Orion Nebula cluster (C 0532-054)
      Tian K.P., Van Leeuwen F., Zhao J.-L., Su C.G.
    <Astron. Astrophys. Suppl. Ser. 118, 503 (1996)>
    =1996A&AS..118..503T      (SIMBAD/NED BibCode)
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ADC_Keywords: Clusters, open ; Proper motions
Keywords: open clusters - C 0532-054 - astrometry

Description:
    Relative proper motions and membership probabilities for 333 stars
    within an area of 1.6deg by 1.8deg centred on the Orion Nebula M 42
    are determined using plates taken over a period of 83 years with the
    double astrograph of Shanghai Observatory (scale of 30"/mm). The
    plates were measured with the ASTROSCAN automatic plate-measuring
    machine of Leiden Observatory. The average proper motion accuracy
    obtained for stars in the photographic magnitude range 7 to 14 is
    0.3mas/yr. Errors are somewhat larger towards fainter and brighter
    magnitude, but the majority lie well below 1mas/yr. 64% of the stars
    have been measured successfully on at least 13 out of 18 plates. The
    number of stars with membership probabilities higher than 0.7 is 184.
    It is shown by a detailed discussion that the proper motions and
    membership probabilities of the stars determined in this paper are in
    good agreement with the results presented recently by other authors.
    Although there is a clear concentration in the proper motion diagram,
    both the remaining dispersion of the internal motions and the
    distribution of "members" as projected on the sky indicate that the
    stars in this region are not bound as one system, but do have a common
    origin. A similar conclusion can be drawn from a comparison with
    spectroscopic and radial velocity data.

Objects:
    ------------------------------------------------------
       RA   (2000)   DE    Designation(s)
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     05 35.4      -05 23   C 0532-054 = M 42 = Ori Nebula
    ------------------------------------------------------

File Summary:
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  FileName      Lrecl  Records   Explanations
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ReadMe             80        .   This file
table3            100      333   Results of the astrometric study
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See also:
    II/171 : PARENAGO Catalogue of stars in the area of the Orion Nebula

Byte-by-byte Description of file: table3
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   Bytes Format Units    Label     Explanations
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   4-  6  I3    ---      No        [1/406]+ Sequential number
  10- 13  I4    ---      Parenago  Parenago number (Catalogue <II/171>)
  17- 21  F5.2  mag      Pmag      Photographic magnitude
      25  I1    h        RAh       Right ascension (J2000, Epoch 1950)
  28- 29  I2    min      RAm       Right ascension (J2000, Epoch 1950)
  32- 37  F6.3  s        RAs       Right ascension (J2000, Epoch 1950)
      41  I1    ms     e_RAs       rms uncertainty on RA
      43  A1    ---      DE-       Declination sign
      44  I1    deg      DEd       Declination (J2000, Epoch 1950)
  47- 48  I2    arcmin   DEm       Declination (J2000, Epoch 1950)
  51- 55  F5.2  arcsec   DEs       Declination (J2000, Epoch 1950)
  58- 59  I2    mas    e_DEs       rms uncertainty on DE
  62- 66  F5.1  mas/yr   pmRA      Proper motion along RA
  69- 71  F3.1  mas/yr e_pmRA      rms uncertainty on proper motion RA
  74- 78  F5.1  mag/yr   pmDE      Proper motion in DE
  81- 83  F3.1  mag/yr e_pmDE      rms uncertainty on proper motion DE
  87- 88  I2    ---      Plate     Number of plates used
  91- 95  F5.1  yr       Ep-1950   Mean epoch in years, relative to 1950.0
  99-100  I2    %        Memb      Membership probability in percents
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References:
  Parenago, P.P. 1954, Trudy Sternberg Astron.Inst. Vol.25 =Catalogue <II/171>
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(End)                                         Patricia Bauer [CDS]   06-May-1996