Echoes of multiple outbursts of Sagittarius A⋆ revealed by Chandra M. Clavel, R. Terrier, A. Goldwurm, M. R. Morris, G. Ponti, S. Soldi and G. Trap A&A, 558 (2013) A32 Published online: 30 September 2013 DOI: 10.1051/0004-6361/201321667