1. Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
2. School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
3. Institute for Astronomy, University of Hawai’i, Honolulu, HI 96822, USA
4. Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, UK