VERITAS Observations of Mkn 501 in 2009
  VERITAS is the high-sensitivity instrument of latest generation. It is often
used for the short AGN monitoring exposures evenly distributed over entire
observational season of a source of interest. Each of these exposures is long
enough to detect the source at the flux level of about 1 Crab. During the 2009
observing season a number of exposures of Mkn 501 with VERITAS revealed
variable TeV gamma-ray emission at the flux level eventually exceeding 2 Crab.
The spectral and flux variability measurements in TeV gamma rays for the 2009
data sample of Mkn 501 are summarized in this paper.
