2 The catalogue

In this new open cluster catalogue we used previous ones such as the WEBDA, ESO Catalogue (Lauberts 1982) and Lyngå (1987) as a starting point. The basic data contained in these catalogues are coordinates, age, apparent diameter, colour excess, and distance. We inserted new objects, and when available, kinematical and metalicity data. We made extensive use of the Simbad database and of the literature to find data on the clusters or on individual stars of the clusters, to obtain radial velocities and proper motions averaged over a number of stars. We do not claim, however, that the catalogue is the result of a complete survey of all the bibliography on open clusters.

Our catalogue (Table 1a) consists of a single list of fundamental parameters and kinematical data, with bibliographic notes. The file is self-explanatory and fully documented internally. The present version of the catalogue includes information for 1537 open clusters. For each cluster we list its equatorial coordinates in J2000.0 and the following parameters, when available: angular apparent diameter; distance; colour excess; age; mean proper motions and errors; number of stars used in the proper motion computation and references; mean radial velocity and error; number of stars used in the radial velocity determination and references; mean metalicity and errors; number of stars used in the metalicity determination. An identical list (Table 1b) is also provided with positions and proper motions in galactic coordinates. The full bibliographic references are given in a separate file (Table 2).

In total, 94.7$\%$ of the objects have estimates of their apparent diameters, and 37$\%$ have distance, E(B-V) and age determinations. Concerning the data on kinematics, 18$\%$ have their mean proper motions listed, 12$\%$ their mean radial velocities, and 9$\%$ have both information simultaneously.

Many objects in the list were visually checked in the Digitized Sky Survey (DSS) plates, and in several cases the central coordinates of the clusters were corrected. This is the case of clusters like Lynga 8, Stock 12, Stock 15 and vdB-Hagen 164, just to mention a few, that present great differences in position.

Throughout our visual inspection of the DSS plates, there were also many cases in which no cluster could be found (e.g. several Ruprecht, Collinder and Loden clusters), even in large fields around their catalogued coordinates. They were nevertheless kept in the catalogue, but a comment was added. We shall refer to these "objects'' as "non-identified clusters''. Among these, are the NGC objects flagged as "non-existent'' in the The Revised New General Catalogue of Non stellar Astronomical Objects (RNGC) (Sulentic & Tifft 1973). On the other hand, some clusters noted as "non-existent'' in the RNGC seem to be actual clusters (e.g. NGC 2017, NGC 2609, NGC 3036, NGC 5800, NGC 6115, NGC 6444). These have been marked as "recovered'' in our catalogue.

A complementary table (Table 3) of the clusters with available photometric data was also built. Table 3 consists of four columns: cluster name; bands observed with CCD; bands observed with photomultipiers; bands observed with photographic plates. For each cluster, only bands with more than ten observed stars are listed. At the present, the table only lists the UBVRI bands, but it will be extended to other commonly used photometric systems (e.g. $uvby \beta$, Geneva, Washington, Vilnius, etc.). The data table was assembled using data collected from WEBDA and from searches in the literature.