VERITAS Philosophy

The philosophy underlying VERITAS comes from 30 years of development of atmospheric Cherenkov telescopes at the Whipple Observatory; the objective is to build a VHE gamma-ray observatory which will have a useful lifetime well into the next century. The field of ground-based gamma-ray astronomy has grown rapidly in the last decade due to the exciting discoveries by EGRET and Cherenkov telescopes. This growth is reflected in the composition of the VERITAS project. A number of new groups have joined the original Whipple Collaboration to formulate this proposal. These groups bring important technical expertise that will allow the expanded collaboration to carry out a project of this scale.

The VERITAS proposal is to build an array of seven telescopes of 10m aperture; each telescope will be closely based on the proven design of the Whipple 10m optical reflector. The power of arrays of imaging telescopes has been demonstrated and recently discussed in the literature ([Krennrich et al. 1998]; [Konopelko et al. 1999]).

The detailed design of VERITAS is based on the following considerations:

$\bullet$

Proven technique: The method of detection will be the atmospheric Cherenkov imaging technique which is now under considerable development at a number of centers.

$\bullet$

Proven Technology: The experience gained in the construction and operation of the 10m reflector (built in 1968) and the camera (built 1987-99) will be adhered to wherever possible. However, we will incorporate significant innovations introduced by ourselves and our colleagues at other observatories if they have proven to be effective.

$\bullet$

Modular Construction: We will build one prototype telescope as quickly as possible and demonstrate that it meets its design criteria at the new site. The existing 10m telescope will be operated throughout the construction phase and will serve as a test-bed for innovative technologies; it may ultimately become an eighth, non-standard element of the array. By building the additional telescopes over a five year period, we hope to be operational at all times.

$\bullet$

Versatility: With an array many experimental configurations are possible. The maximum sensitivity is achieved when all telescopes are operated in parallel, but there will be instances when different operating modes will be desirable. These vary from operation as discrete telescopes which monitor several sources, to operation of sub-arrays which obtain accurate measurements of stronger sources. It will also be possible to test experimental configurations in coincidence with normal telescope operation.

$\bullet$

Location: The array should be located where it has high operating efficiency, the construction costs are modest and there is existing infrastructure. Arizona offers some of the best observing conditions in the world and has the advantage of easy accessibility to most of the participating institutions. The Smithsonian Institution is a major sponsor of the project and there are suitable dark sites close to the Whipple Observatory which will provide the necessary infrastructure.

$\bullet$

Cost: The capital cost of the proposed facility will be larger than that of any previously built ground-based gamma-ray observatory, but economical in terms of scientific return. The cost of VERITAS (Section 7) will be less than 10% of the GLAST mission, now estimated to cost at least $300 million.