Discovery of diffuse radio emission in the galaxy cluster A1689 V. Vacca, F. Govoni, M. Murgia, G. Giovannini, L. Feretti, M. Tugnoli, M. A. Verheijen and G. B. Taylor A&A, 535 (2011) A82 Published online: 11 November 2011 DOI: 10.1051/0004-6361/201117607