1. Kapteyn Astronomical Institute, University of Groningen, PO Box 800, NL-9700 AV Groningen, the Netherlands
2. STAR Institute, Quartier Agora, Allée du Six Août, 19c, B-4000 Liège, Belgium
3. INAF – Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, I-80131 Napoli, Italy
4. Lorentz Institute for Theoretical Physics, Leiden University, PO Box 9506, NL-2300 RA Leiden, the Netherlands
5. Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden, the Netherlands
6. Dipartimento di Fisica e Astronomia, Università di Bologna, Via Gobetti 93/2, I-40129 Bologna, Italy
7. INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Gobetti 93/3, I-40129 Bologna, Italy
8. Institute of Physics, Laboratory of Astrophysique, École Polytechnique Fédérale de Lausanne (EPFL) , Observatoire de Sauverny, CH-1290 Versoix, Switzerland