The BL-Lacertae gamma-ray blazar PKS 1424+240 associated with a group of galaxies at z = 0.6010 A. C. Rovero, H. Muriel, C. Donzelli and A. Pichel A&A, 589 (2016) A92 Published online: 19 April 2016 DOI: 10.1051/0004-6361/201527778