1. Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
2. Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599, USA
3. AAVSO, 49 Bay State Rd Cambridge, MA 02138, USA
4. Centre for Astronomy, National University of Ireland Galway, Galway, Ireland
5. Institute for Astronomy and Astrophysics, Eberhard Karls University, Sand 1, D-72076 Tübingen, Germany
6. Institut für Theoretische Physik und Astrophysik, Universität Kiel, D-24098 Kiel, Germany
7. INAF–Astronomical Observatory of Padova, I-36012 Asiago (VI), Italy
8. Centre for Astrophysics Research, STRI, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK