1. Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
2. Max-Planck-Institut für Astronomie, Königstuhl, Heidelberg, Germany
3. UCLA, Department of Physics and Astronomy, LA, CA 90095, USA
4. National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China
5. Astro Space Center, Lebedev Physical Institute, Russian Academy of Sciences
6. Abastumani Observatory, Mt Kanobili, 0301 Abastumani, Georgia
7. Engelhardt Astronomical Observatory, Kazan Federal University, Tatarstan, Russia
8. Astronomical Institute, Academy of Sciences, Boční II 1401, CZ-14131 Prague, Czech Republic
9. I. Physikalisches Institut der Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
10. University of Michigan, Ann Arbor, MI 48109, USA
11. Tuorla Observatory, Department of Physics and Astronomy, University of Turku, 20500, Turku, Finland
12. Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Gran Bretaña No. 1111, Playa Ancha, 2360102 Valparaíso, Chile
13. Instituto de Astrofísica, Pontificia Universidad Católica de Chile, 782-0436 Santiago, Chile