[1] Osservatorio Astron Capodimonte, I-80131 Naples, Italy
[2] Australian Natl Univ, Mt Stromlo & Siding Spring Observ, Weston, ACT 2611, Australia
[3] Univ Basel, Inst Astron, CH-4102 Binningen, Switzerland
[4] Munich Univ Observ, D-81679 Munich, Germany
[5] Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA