Contents

• Overview

• Design

• Scientific Objectives

• Our involvement in the project

Overview

VERITAS, the Very Energetic Radiation Imaging Telescope Array System, is an array of four 12m aperture optical reflectors used for gamma-ray astronomy in the 50 GeV to 50 TeV energy range. These atmospheric Cherenkov telescopes use the imaging concept developed by the Whipple Observatory Gamma-Ray Collaboration, detecting faint traces of light created when high energy gamma rays interact with the Earth's atmosphere. Construction began in 2003, and the full array was completed in spring of 2007.

Design

Each telescope has a tessellated 12 m mirror and long focal length (12 m) with the optical design optimized for good angular resolution, a large field of view, minimum wavefront distortion, and identical, spherical mirror facets. Each telescope camera has 499 pixels covering a 3.5° field of view with 0.15° resolution. The total array has an effective collection area in excess of 10,000 m^2. VERITAS is located in southern Arizona where it takes advantage of the existing infrastructure of the Whipple Observatory . With stereoscopic imaging, the array achieves an unprecedented angular resolution, energy resolution, and background rejection over three decades of energy.

Scientific Objectives

The primary scientific objectives of VERITAS are the study of active galactic nuclei , supernova remnants , pulsars, gamma-ray bursts, evidence of dark matter, and the search for new sources. A source with 1% of the flux of the Crab Nebula is detectable after observing for 47 hours. For a 5% Crab source, observation time falls to 2.5 hours. The angular resolution of (<0.1 deg) for a single event is possible when using all four telescopes (averaged over all energies.) Resolution of (<0.5 deg) can be sufficient to identify a number of unidentified sources detected by EGRET on the Compton Gamma Ray Observatory. VERITAS provides a unique combination of large collection area, low background, and good energy resolution. It effectively complements Fermi telescope , the newest major high-energy gamma-ray space telescope; together they may solve the problem of the origin of the cosmic radiation as well as probe fundamental questions of physics and cosmology.

Our involvement in the project

Previously, our group designed electronics for use with VERITAS and helped define the scientific objectives of the experiment. This includes custom Flash Analog-to-Digital Converter (FADC) circuitry which converts the Cherenkov pulse waveform into digital data and maximizes the signal-to-noise ratio for detecting Cherenkov flashes. Currently, group members analyse data taken with VERITAS on various sources. They investigate methods to improve the performance of VERITAS (e.g. investigating the effects that moving a telescope would have on the instrument's resolution.) We are also helping to develop the next gereation of gamma-ray telescope, the Advanced Gamma-ray Imaging System (AGIS). Members also spend time at the observatory in Arizona, helping take data for the entire collaboration.