First IBIS results on the high energy emission of Cygnus X-2 L. Natalucci, M. Del Santo, P. Ubertini, F. Capitanio, M. Cocchi, S. Piraino and A. Santangelo A&A, 411 1 (2003) L395-L398 Published online: 17 November 2003 DOI: 10.1051/0004-6361:20031421