An ultraminiature atomic clock.

Neither gaining nor losing as much as a millionth of a second in a year, the NIST-7 atomic clock sets the standard for timekeeping (SN: 5/1/93, p.276). But it's an expensive, bulky clock, ill- suited for everyday use in navigation or telecommunications. Sacrificing a little accuracy, researchers at Westinghouse Electric Corp. in Pittsburgh have now developed a compact atomic clock that can easily fit into radio receivers and other types of electronic equipment, greatly improving their ability to track time and to synchronize signals.