This atomic clock was used at the Goldstone Time Standards Laboratory in 1970, to synchronize clocks at Deep Space Network stations around the world. This master clock was accurate to plus or minus two millionths of a second, when compared to clocks maintained by the National Bureau of Standards and the U.S. Naval Observatory. In the late 1960s, JPL had developed a moon bounce technique to transmit signals from one deep space antenna to another. Experiments included periodic measurement of timing signals that were reflected from the surface of the moon, to find out if the station clocks were within allowable limits for accuracy.