It took two years of hard work, but finally, on March the 12th, NASA announced that Sentry, its new automatic asteroid impact monitoring system, was beginning to be operated out of Jet Propulsion Laboratory. Sentry was built largely by Drs. Steve Chesley and Alan Chamberlin with technical help from Paul Chodas. To be more precise, Sentry is a highly automated system, designed to help scientists better communicate about the discoveries of new, potentially threatening Near Earth asteroids (NEAs) and their follow-up observations. While completely independent from other scienitific teams, it is in constant communication with the NEODyS CLOMON impact monitoring system, operated in Pisa, and researchers from the two systems are cooperating to check and improve their results.