I built a "ufo detector" consisting of a strong magnet suspended by wire and passing through a small loop of wire. if the magnet moved and touched the small loop a bell would ring. constantly went off with military jets. one late afternoon my parents and about eight neighbors were outside either chatting or doing something in the yard. bell went off on the detector and all of us saw a shiny disc hovering over some homes a block away. then it started silently moving se to sw and then took off at high speed and disappeared.
it's been a long time since it happened but i wanted to mention the simple "ufo detector" and the amount and location of witnesses.