1. SKA Organization, Jodrell Bank, Lower Whitington, Macclesfield SK11 9DL, UK
2. INAF – Istituto di Radioastronomia, and Italian ALMA Regional Centre, Via Gobetti 101, I-40129, Bologna, Italy
3. INAF – Osservatorio Astronomico di Padova, Vicolo Osservatorio 5, I-35122, Padova, Italy
4. INAF – Osservatorio Astronomico di Trieste, Via Tiepolo 11, I-34143, Trieste, Italy
5. Jodrell Bank Centre for Astrophysics, School of Physics & Astronomy, The University of Manchester, Manchester M13 9PL, UK