Most accurate clock people have now a days is their cell phone!
In the fall of 1966 at the USCG Loran C station in Sattahip Thailand that I helped build, we installed rubidium oscillators in the Loran timers and the rumor spread across the war zone that the Coast Guard in Sattahip had atomic time! And the phone started ringing at o dark thirty each morning for time checks.
In reality we had a windup black military clock set to GMT on the radio room wall and listen to WWV(Fort Collins, Co) or WWVH(Hawaii) a few times a week to assure it was correct.
So we timed many battles of the Vietnam war!!!
