3. The catalogue

3.1. The catalogue

In a first file, we present the catalogue itself, giving for each star identifications, coordinates, visual magnitude, and the mean values of the photoelectric data concerning the star and the data sources. The information contained in the columns of this file is as follows:

1. LID, a code number for stellar identification
2. Remarks on duplicity/variability
3. HD, HDE number
4. DM number
5. ID acronyms and cross-identification
6. Co-ordinates for equinox 1950
7. , number of sources used for the mean
8. Mean V magnitude. In the 148 cases where V was not published by the authors, we have introduced the mean V magnitude from the UBV system (Mermilliod & Mermilliod 1994)
9. 
10. Mean b-y colour index
11. (b-y)
12. Mean m₁ colour index
13. 
14. Mean c₁ colour index
15. 
16. , cumulated number of measurements
17. Mean colour index
18. ()
19. NB, cumulated number of measurements
20. Ref, key of the data sources.

3.2. The measurements

The second file contains the individual measurements for each star with the code number LID and the remarks (see Sect. 3.1, items 1 and 2), the V magnitude, the colours b-y, m₁, c₁ with the number of measurements, the parameter with the number of measurements, and the key of the data source.

3.3. Coordinates

Coordinates are very important for performing selections based on the position in the sky. We have also made an effort to collect co-ordinates from the literature or the database for stars in open clusters (Mermilliod 1995) so that it will be posssible to query the catalogue by positions.

3.4. Data sources

As a rule, all astronomical journals are surveyed for new photometric data. The bibliographic references (data sources) are collected in a separate part (file 3). The reference numbers are generally attributed sequentially in order of arrival. The information entered in the file is the source number, the list of authors' names, the journal information (year, name, volume, page), the complete title, and the ADS/CDS bibliographic code to enter the ADS Abstract Service system.

3.5. Stellar identifications

In the last part of our catalogue, in file 4, we present all the acronyms used for the stellar identification (see Sect. 3.1, item 5) in alphabetic order and in respect of the convention of Fernandez et al. (1983). One of our main contributions concerns the stellar identifications. When necessary, we have transformed the published identifications into a uniform system: various names are used in the literature, generally depending on the kind of sample investigated, and the most time-consuming work is related to the necessity of collecting all the data for each star under the same identification, otherwise the advantage of working on large compilations partly vanishes. The basic principles adopted for this work have been explained in the description of the code numbering system (Mermilliod 1978) and the solution designed for star clusters is described by Mermilliod (1976).