  We report on observations of very high-energy gamma rays from the shell-type
supernova remnant Cassiopeia A with the VERITAS stereoscopic array of four
imaging atmospheric Cherenkov telescopes in Arizona. The total exposure time
for these observations is 22 hours, accumulated between September and November
of 2007. The gamma-ray source associated with the SNR Cassiopeia A was detected
above 200 GeV with a statistical significance of 8.3 s.d. The estimated
integral flux for this gamma-ray source is about 3% of the Crab-Nebula flux.
The photon spectrum is compatible with a power law dN/dE ~ E^(-Gamma) with an
index Gamma = 2.61 +/- 0.24(stat) +/- 0.2(sys). The data are consistent with a
point-like source. We provide a detailed description of the analysis results,
and discuss physical mechanisms that may be responsible for the observed
gamma-ray emission.
