Our old place had a large sliding patio door that got the morning sun. The wife had hung an assortment of prisms and crystals that would rattle gently at about 9:20 am. All I've been able to figure is the residual shock wave from the Concorde into JFK. Probably left Europe around 11 am, 3+ hr flight, 5 hr time difference - goes along with the 9:20am rattle.