1. Department of Physics, Virginia Tech, Blacksburg, VA 24061, USA
2. Department of Physics and Astronomy, University of Hawaii, 2505 Correa Road, Honolulu, HI 96822, USA
3. Institute for Astronomy, 2680 Woodlawn Drive, University of Hawaii, Honolulu, HI 96822, USA
4. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
5. The Observatories of the Carnegie Institution for Science, 813 Santa Barbara St., Pasadena, CA 91101
6. Instituto de Astrofísica e Ciências do Espaço, Universidade de Lisboa, OAL, Tapada da Ajuda, PT1349-018 Lisboa, Portugal
7. Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Edifício C8, Campo Grande, PT1740-016 Lisbon, Portugal
8. School of Sciences, European University Cyprus, Diogenes Street, Engomi, 1516 Nicosia, Cyprus
9. ESO, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
10. National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA
11. Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam, Germany
12. Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK