Gamma-ray Bursts

Recent detections of X-ray and optical afterglows confirm the initial BATSE indications that at least one subset of gamma-ray bursts (GRBs) have an extragalactic origin. However, the sources and mechanism for producing the GRBs remain unknown. The detection of an 18GeV photon from a GRB more than 90 minutes after the burst was detected by BATSE ([Hurley 1994]) demonstrates that high energy gamma-rays play an important role in the energetics of GRBs. Also, because the high energy emission can be delayed, it can be pursued with rapid follow-up observations. More recently, the Milagro Collaboration has reported a weak ( $\sim 3\sigma$) detection of TeV emission from a GRB ([McEnery et al. 1999]) raising the possibility that TeV photons may carry a significant fraction of the energy emitted in a GRB. Because of its low energy threshold, VERITAS will be able to see bursts out to z$\sim$1 or more. The large field of view of VERITAS (up to 10$^\circ$ with all telescopes pointing in slightly different regions of the sky), rapid slew speed and good angular resolution make it an excellent telescope for conducting counterpart searches. Because of the difficulty in producing VHE gamma-rays and in getting them out of the region where the burst originates, accurate measurements of a VHE component would place stringent new limits on the viable models for GRBs. In addition, the expected attenuation at high energies from interaction with background IR fields would establish the distance scale of GRBs using the high energy photons themselves.