servations.
2. VERITAS
VERITAS, a stereoscopic array of four 12-m
atmospheric-Cherenkov telescopes located in Arizona,
is used to study VHEγ-rays from a variety of astro-
physical sources [4]. VERITAS began scientiﬁc obser-
vations with a partial array in September 2006 and has
routinely observed with the full array since Septem-
ber 2007. The performance metrics of VERITAS in-
clude an energy threshold of∼ 100 GeV, an energy
resolution of ∼ 15%, an angular resolution of ∼ 0.1◦,
and a sensitivity yielding a 5 σ detection of a 1% Crab
Nebula ﬂux object in <30 hours 1. VERITAS has an
active maintenance program (e.g. frequent mirror re-
coating and alignment) to ensure its continued high
performance over time, and an upgrade improving
both the camera (higher quantum-eﬃciency PMTs)
and the trigger system has been proposed to the fund-
ing agencies.
1A VERITAS telescope was relocated during Summer 2009,
increasing the array’s sensitivity by a factor ∼ 1.3.
eConf C091122