Photoelectric Photometric Catalogue of Homogeneous Measurements in the UBV System Mermilliod, J.-C. 1991, Institut d'Astronomie, Universite de Lausanne, CH-1290 Chavannes-des-Bois, SWITZERLAND The first homogeneous catalog of UBV photoelectric data was published in 1978 by Nicolet and covered the time period 1953-1975. It was based on the compilation of observations by Mermilliod & Nicolet (1977). Since that time, an additional 40,000 stars have been measured or located in the literature. The present catalog is based mainly on the compilation of individual observations by Mermilliod (1987b), but has been updated with newer observations of approximately 5,000 stars. An analysis of the compilation of individual observations can be found in Mermilliod (1987a). The homogenization procedure used by Nicolet (see Nicolet & Hauck 1977) attempted to refer all lists back to the standard system by comparing each published list to a reference list, then assigning a weight to each. The calculation of homogeneous means for each star was based on the assigned weights for each list containing that star. The procedure used for the new catalog differs in that no attempt was made to analyze each list individually by comparing it against a reference list. The reasons for adopting the new procedure are: 1. The number of references is now more than 1500 and it is no longer feasible to analyze each one with respect to a reference list. 2. The numbers of stars in many lists are often so few that the comparisons with the reference list have little meaning. Sometimes there are no common stars at all and one faces a dilemma, in which case another method must be used anyway. 3. Erratic errors (author errors, misprints, etc.) are rather frequent and are often not readily identifiable as such by the sizes of their deviations. The procedure adopted for this catalog involves two steps: 1. Normal averages are computed, weighted by the number of observations in each list. When such a number of observations is not published, unit weight was assigned. 2. The deviation of each value from the above mean is determined, followed by a second computation of the mean that now uses a weight that accounts for the deviation. Although the new technique is not as rigorous as that of comparing each list directly against the standard system, it does give lower weight to discrepant values, albeit independently of the real reasons for the errors, which in many cases cannot be found. All discovered discrepancies have been rechecked against the published data to ensure that a minimal number of errors have been introduced during the course of this work. A list of unresolved errors found in the original compilation was published by Mermilliod (1987c) and might be used in conjunction with the present catalog if apparent discrepancies are found. The catalog consists of a single data file. Table 1 contains a description of the record format. The record length is 72 and there are 92,964 records in the file. A description of the coded numbering as it applies to this specific catalog is given in a second file. The file consists of 80-byte logical records and is in mixed-case-text format. There are 2630 records in the numbering system file. Table 1. Format Description. Catalogue (Mermilliod 1991). ======================================================================== Column Byte(s) Format Description ------------------------------------------------------------------------ 1 1-10 A10 Lausanne identification number (Mermilliod 1978) consisting of a 10-digit number followed by 11 A1 component (D, 1, 2, ...). The "D" indicates that more than one component of a multiple system was included in the diaphragm when the observation was made. 12 A1 Variability (V) code. 2 14-15 I2 Number of publications (separate lists) contributing observations to the means. 3 17-22 F6.3 . Precision varies. 4 25-29 F5.3 Standard deviation for . 5 31-34 A1,I3 Number of observations for . Byte 31 may contain a lower-limit character (>). 6 36-41 F6.3 . Precision varies. 7 44-48 F5.3 Standard deviation for . 8 50-53 A1,I3 Number of observations for . Byte 50 may contain a lower-limit character (>). 9 55-60 F6.3 . Precision varies. 10 63-67 F5.3 Standard deviation for . 8 69-72 A1,I3 Number of observations for . Byte 69 may contain a lower-limit character (>). ======================================================================== References ---------- Mermilliod, J.-C. 1978, Bull. Inform. CDS No. 14, p. 32 Mermilliod, J.-C. 1987a, A&AS, 71, 119 Mermilliod, J.-C. 1987b, A&AS, 71, 413 Mermilliod, J.-C. 1987c Bull. Inform. CDS No. 32, p. 37 Mermilliod, J.-C., & Nicolet, B. 1977, A&AS, 29, 259 Nicolet, B. 1978, A&AS, 34, 1 Nicolet, B., & Hauck, B. 1977, in Compilation, Critical Evaluation and Distribution of Stellar Data, ed. C. Jaschek & G. A. Wilkins (Dordrecht, Reidel), p. 121