Aharonian, F.Akhperjanian, A.Barrio, J.Bernlohr, K.Borst, H.Bojahr, H.Bolz, O.Contreras, J.Contina, J.Denninghoff, S.Fonseca, V.Gonzalez, J.Gotting, N.Heinzelmann, G.Hermann, G.Heusler, A.Hofmann, W.Horns, D.Ibarra, A.Iserlohe, C.et al.2007-08-292007-08-292001Astronomy and Astrophysics (A & A), 2001; 370(1):112-1200004-63611432-0746http://hdl.handle.net/2440/37585232 hours of data were accumulated from 1997 to 1999, using the HEGRA Stereoscopic Cherenkov Telescope System to observe the supernova remnant Cassiopeia A. TeV γ-ray emission was detected at the 5 σ level, and a flux of (5.8 ± 1.2<inf>stat</inf> ± 1.2<inf>syst</inf>) 10^-9 ph m^-2 s^-1 above 1 TeV was derived. The spectral distribution is consistent with a power law with a differential spectral index of -2.5 ± 0.4<inf>stat</inf> ± 0.1<inf>syst</inf> between 1 and 10TeV. As this is the first report of the detection of a TeV γ-ray source on the "centi-Crab" scale, we present the analysis in some detail. Implications for the acceleration of cosmic rays depend on the details of the source modeling. We discuss some important aspects in this paper.en© The European Southern Observatory 2001Journal article002007127110.1051/0004-6361:200102430001686824000182-s2.0-003531473848502Rowell, G. [0000-0002-9516-1581]