II/168      Homogeneous Means in the UBV System (Mermilliod 1991)
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Catalogue of Homogeneous Means in the UBV System
    Mermilliod J.C.
   <Institut d'Astronomie, Universite de Lausanne (1991)>
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ADC_Keywords: Photometry, UBV


Description:
    The present catalog supersedes an earlier edition of Nicolet (1978).
    It is a collection of weighted mean photoelectric values (V, B-V, U-B)
    for stars measured in the UBV system. The mean values were computed by
    combining all individual measurements compiled in the catalog of
    Mermilliod (1987), except those that were clearly found to be
    erroneous for some reason or another. Some newer observations compiled
    since 1987 are also included in the means. The procedure for computing
    the homogeneous means involved the calculation of normal averages
    weighted by the number of observations in each list (unity when not
    published). New weights are assigned based on the deviation of each
    value from the previous mean, then a new weighted mean is computed.

    This technique is not as rigorous as that used by Nicolet (comparison
    of each list with the standard system master list), but the latter
    cannot often be realized effectively in practice, since many lists do
    not contain enough stars in common with a standard list. Also, there
    are now so many references (more than 1500) that it is not feasible to
    analyze each publication with respect to a standard list. This edition
    of the catalog contains 92964 stars measured since the introduction of
    the UBV system in 1953. The data included are star identification in
    the Geneva coded numbering system, double and variable codes, UBV data
    and their standard deviations, and number of observations. A second
    file contains the definition of the coded numbering system.

    The catalog was prepared at the Institut d'Astronomie de l'Universite
    de Lausanne in Geneva.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
ubvmeans.dat      72    92964   Catalog Data
doc.txt           72      100   Author's documentation
coding.txt        80     2630   Numbering system documentation


Byte-by-byte Description of file:  ubvmeans.dat

   Bytes Format  Units  Label   Explanations

   1- 10  A10    ---    LID     Lausanne identification number (1)
      11  A1     ---    m_LID   Lausanne component (D, 1, 2, ...) (1)
      12  A1     ---    var     [V] Variability code.
  14- 15  I2     ---    Npub    Number of publications (separate lists)
                               contributing observations to the means
  17- 22  F6.3   mag    Vmag    ?Mean V magnitude (Precision varies)
  25- 29  F5.3   mag    e_Vmag  ?Standard deviation for Vmag
      31  A1     ---    n_Vmag  [>S/] Standard (S) or note on o_Vmag (2)
  32- 34  I3     ---    o_Vmag  ?Number of observations for Vmag
  36- 41  F6.3   mag    B-V     ?Mean (B-V) color index (Precision varies)
  44- 48  F5.3   mag    e_B-V   ?Standard deviation for B-V
      50  A1     ---    n_B-V   [>S/] Standard (S) or note on o_B-V (2)
  51- 53  I3     ---    o_B-V   ?Number of observations for B-V
  55- 60  F6.3   mag    U-B     ?Mean (U-B) color index (Precision varies)
  63- 67  F5.3   mag    e_U-B   ?Standard deviation for U-B
      69  A1     ---    n_U-B   [>S/]  Standard (S) or note on o_Vmag (2)
  70- 72  I3     ---    o_U-B   ?Number of observations for U-B

Note (1):
    The Lausanne identification number is comprised of both the LID and
    m_LID fields, detailed in the "coding.txt" file. The "D" in the m_LID
    field indicates that more than one component of a multiple system was
    included in the diaphragm when the observation was made.
Note (2):
    S   indicates standard star
    >   indicates a minimal number of observations
    /   indicates number of observations is unknown


History:
  * 07-Dec-1992: File received at CDS from J.-C. Mermilliod (Lausanne)
  * 05-Sep-1997: Standardisation by James E. Gass [SSDOO/ADC]
  * 07-May-2006: Rewriting of the codes for standard stars (F. Ochsenbein, CDS)

References:
   Mermilliod, J.-C., & Mermilliod, M.: 1994, "Catalog of mean UBV
     data on stars." Springer-Verlag, New York
   Mermilliod, J.-C. 1978BICDS..14...32M, Cat. II/58
   Mermilliod, J.-C. 1987a (1987A&AS...71..119M), Cat. II/122
   Mermilliod, J.-C. 1987b (1987A&AS...71..413M), Cat. II/122
   Mermilliod, J.-C. 1987c (1987BICDS..32...37M), Cat. II/122
   Mermilliod, J.-C., & Nicolet, B. 1977A&AS...29..259M, Cat. II/35
   Nicolet, B. 1978, 1978A&AS...34....1N, Cat. II/51
   Nicolet, B., & Hauck, B. 1977, in Compilation, Critical Evaluation and
     Distribution of Stellar Data, ed. C. Jaschek & G. A. Wilkins
     (Dordrecht, Reidel), p. 121
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(End)    James E. Gass [SSDOO/ADC], Francois Ochsenbein [CDS]        07-May-2006