This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Atomic Clock. The sixth generation of atomic frequency standards at NBS NBS is meters long and provides frequency reference with an accuracy better than one part in When operated as clock this device keeps time with an accuracy of about millionths of second per year It is part of the NBS Atomic Time System which provides the