We thank M. Dietrich, D. Grupe, and U. Thiele for taking spectra for us. We are grateful to M. Dietrich, E. van Groningen, and I. Wanders who made available some software to us. This work has been supported by DARA grant 50 OR94089 and DFG grant Ko 857/13.
© European Southern Observatory (ESO) 1999
Online publication: April 12, 1999