[ntp:questions] National time standard differences
David J Taylor
david-taylor at blueyonder.delete-this-bit.and-this-part.co.uk.invalid
Wed Feb 10 09:05:34 UTC 2010
"David Woolley" <david at ex.djwhome.demon.invalid> wrote in message
news:hksmaf$1cm$2 at news.eternal-september.org...
> David J Taylor wrote:
>> I remember the flying of caesium or other atomic clocks round the
>> world, and that folks had to invoke relativistic corrections. Were
>> these better than microseconds as well?
> That's called Navstar (GPS) and GPS position solutions do have to
> include a general relativity correction to the satellite clocks.
Not today's GPS, but some forty or more years ago:
"The highly accurate HP 5060A cesium-beam atomic clocks gain worldwide
recognition as the "flying clocks" when they are flown from Palo Alto to
Switzerland to compare time as maintained by the U.S. Naval Observatory in
Washington, D.C. to time at the Swiss Observatory in Neuchatel. The atomic
clock was designed to maintain accuracy for 3000 years with only one
second of error. The cesium-beam standard becomes the standard for
I had wondered what accuracy was obtained - i.e. how far was each nation
out - and whether relativistic corrections had been needed for these
"flying clock" tests.
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