SIMBAD references

We have performed a photometric survey of open clusters in the third Galactic quadrant in order to study the star formation history and spatial structure in the Canis Major-Puppis-Vela region. In this paper we describe a catalogue of CCD UBVRI photometry of approximately 65000 stars in the fields of 30 open clusters. The data were obtained and reduced using the same telescope, the same reduction procedures, and the same standard photometric system, which makes this catalogue the largest homogeneous source of open cluster photometry so far. In subsequent papers of this series, colour-colour and colour-magnitude diagrams will be presented which, amongst other uses, will allow the determination of an homogeneous set of cluster reddenings, distances, and ages that will constitute the observational basis for our studies of the spatial structure and star formation history in the third Galactic quadrant.