1 Introduction

The determination of Galactic open cluster parameters such as reddening, age and metallicity is fundamental to understand the structure and evolution of the Galactic disk. Old and intermediate-age open clusters are excellent probes of early disk evolution, while young open clusters provide information about current star formation processes and they are key objects to delineate Galactic structure. Open clusters located in the direction of the Galactic centre are particularly important to improve our knowledge of the chemical evolution of the inner Galactic disk (see, e.g., Friel & Janes 1993; Piatti et al. 1995). Many of these clusters, however, have not been studied in detail yet because they are affected by high interstellar absorption and/or strong field star contamination.

Fundamental open cluster parameters have been mostly derived from colour-magnitude diagrams (CMDs) and/or photometric studies of individual giants (see, e.g., Janes et al. 1988; Batinelli & Capuzzo-Dolcetta 1991 and references therein; Clariá & Mermilliod 1992; Meynet et al. 1993; Friel 1995; Clariá et al. 1999). Sometimes, however, integrated spectra can provide valuable independent information about reddening, age and metallicity (see, e.g., Piatti et al. 1998a, 1998b, 1999).

The present work is part of a systematic spectroscopic survey of open and globular (or candidates) clusters mostly located toward the Galactic centre. CCD integrated spectra of small objects, from which it is very difficult to obtain individual information about stars unaffected by contamination, are useful not only to recognize the nature of these objects (Bica et al. 1995), but also to determine fundamental parameters of open and globular clusters (see, e.g., Santos & Bica 1993; Piatti 1996; Bica et al. 1998).

In this paper we increase the sample of Galactic open clusters with integrated spectroscopy. Our aim is to derive reddening and age for a sample of 7 unknown or poorly known open clusters mostly located toward the Galactic centre by means of flux-calibrated integrated spectra. In some cases we also provide information about cluster metallicity. In the next section we present the spectroscopic observations and measurements of equivalent widths for absorption features. The procedures employed to derive age, reddening and metallicity are explained in Sect. 3. Individual objects are discussed in Sect. 4. A comparison with other clusters located in similar directions is given in Sect. 5, and the final conclusions are presented in Sect. 6.