This research was partially supported by the Italian "Ministero dell'Università e della Ricerca Scientifica e Tecnologica" (MURST) under the scientific project "Stellar Evolution" (coordinator V. Castellani). R.O. and J.-E.S. acknowledge support from the Norwegian Research Council for use of the Nordic Telescope, including grant no 129280/431 for development of the CCD-photomer; and, together with R.K., the NATO Linkage Grant 972172 and NorFA grant 99.10.003-B for analyzing and improving the results. H.E. acknowledges financial support by the german research foundation DFG under grant He 1354/30-1. The authors would like to thank the NOT technical operations staff in La Palma for their generous support during the two runs in July and October 1999.
© European Southern Observatory (ESO) 2000
Online publication: July 13, 2000