K. Ragan
McGill University

Ground-based gamma-ray astronomy with STACEE and VERITAS

Ground based gamma-ray astronomy in the energy regime above
approximately 50 GeV is being pursued
with two different, and complementary approaches. Both efforts
use the air Cherenkov technique to detect the Cherenkov signal
from high energy secondaries produced by the interaction of
gamma rays of astrophysical origin with the atmosphere.
The first is the STACEE detector using the large mirror area
of a solar power installation as the basis for a wave-front
detector; it aims at reducing the energy threshold compared to
existing instruments, at the expense of sensitivity. The second
approach is the construction of an array of imaging detectors similar
to the venerable Whipple telescope, to achieve unprecedented
sensitivity at slightly higher thresholds. This second approach is
pursued in the VERITAS project which is in the initial stages of
construction in Arizona. We will report on some of the results from the
STACEE detector, now operational in New Mexico, and on the status of
the VERITAS project.