STAR: Very Large Aperture Telescope Array Using Many Small IACTs

Through the experience gained from the past generation of imaging air Cherenkov telescopes (IACTs), it has become evident that both large aperture and multiple telescopes are necessary to obtain a low gamma-ray threshold while rejecting muons. However, the costs associated with building very large ( > 30 m) diameter telescopes is prohibitive. The Small Telescope Array (STAR) is a new design concept for an IACT that achieves a large effective aperture by using many ( > 144) small (2.5 m) telescopes, whose signals are delayed and combined before the trigger is generated. Since the aperture and focal length of each telescope will be small, and thus cheap, the fast pixelated camera can also be small, thus opening up several possibilities for novel camera designs. The array design is also versatile since it allows one to form subarrays and create the ideal array of large aperture IACTs. The baseline design for STAR is a stereo system containing multiple subarrays, each with the equivalent light collecting area of a 20-50 meter telescope. This would lead to sensitivities in excess of any currently planned ground based gamma-ray telescopes at thresholds as low as ~20-40 GeV. Thus, sensitive studies of gamma-ray sources at redshifts as high as ~1-2 could be performed on short timescales. STAR has been considered as a possible extension to VERITAS. Monte Carlo studies have been started to investigate the feasibility of the design and to determine the ideal configuration.