The large effective area of VERITAS enables accurate measurements of
extremely short variations in the gamma-ray flux as illustrated in
Figure 5. The left part of the figure shows
Whipple observations of the fastest flare ever recorded at
gamma-ray energies. While the flare is clearly detected, the
structure of the flare is not resolved. The dashed curve in the
figure is a hypothetical flux variation which matches the Whipple
data. The right part of the figure shows a simulation of what VERITAS
would detect above 200GeV. All features of the flare are clearly
resolved. Space-based telescopes do not have the effective area to
map out such low amplitude flares (GLAST would detect 
3 photons
above 1GeV from a flare of this duration and power). The broad
energy coverage of VERITAS will also allow energy-dependent time
delays to be resolved. These short time-scale measurements provide
information about the acceleration, energy loss, and flaring processes
in the jet, the location of the gamma-ray emission, the jet
characteristics, and even ambient photon levels and accretion rates
for the central AGN.
Because of the extreme variability of blazars at all wavelengths, the
best way to understand the physical processes at work in them is to
conduct detailed observations spanning a wide energy range. A crucial
requirement of these studies is consistent, dense temporal coverage of
the object being studied. VERITAS can be divided into two dedicated
sub-arrays of 3-4 telescopes, with one sub-array observing a single
object for as long as it is above the 30
observation
``horizon'' for as many nights as the multi-wavelength campaign lasts.
Thus, VERITAS can provide more complete measurements of flaring
activity and greatly increase the chance of seeing a wide range of
activity in the objects studied. The sensitivity of VERITAS to
short-time scale variations will be an excellent match to X-ray and
optical telescopes, permitting much improved measurements of
energy-dependent variability. The wide energy coverage and good
energy resolution of VERITAS will improve measurements of the blazar's
spectral energy distribution and variability (particularly when
combined with GLAST). Both are rather poorly constrained at this time
but are critical to understanding the emission and flaring mechanisms.
Finally, the flux sensitivity of VERITAS (and its ability to observe
these objects consistently over long periods of time) will permit
measurements of the baseline emission level in blazars, of which
essentially nothing is presently known in the gamma-ray regime.
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