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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.
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