ASHKELON, Israel — Sunday, the first day of the work week, started with a boom in this quiet seaside town. Not a boom, actually, more like: Boom! Boom! Boom! BOOM! The first three were the heart-stopping but by now familiar and comforting sounds of Israel's anti-missile system, Iron Dome, intercepting rockets launched from Gaza high up in the sky. The last, more like a small earthquake, was a rocket the system missed, hitting ground in the middle of town.