saw disk fly in and hover above pond,the pond is about 100 foot dia.We were sitting on the pier,exceptionaly close,you could see every detal on it. I made a whirling noise and every time the main body revolved around the stationary dome on top at a certain point around the periphery a flash of light and a blip sound occured.The underbelly was concave thetop half had a rim that was flat for about a foot towards the center then it was dished down and ran flat to the half spherical dome which did not rotate.as the disc rotated faster the blip and flash occured faster with the increasing rotation.all this time it gave off the spectrum of light in varrying colors around the upper rim,then it took off so fast you would say in the blink of an eye