[time-nuts] Primary Standards...
Lux, Jim (337C)
james.p.lux at jpl.nasa.gov
Wed Feb 24 14:47:29 UTC 2010
On 2/24/10 4:38 AM, "Rob Kimberley" <rk at timing-consultants.com> wrote:
> Yes, and no..
> Time as we know it (UTC) is coordinated at the BIPM in Paris between
> observations from primary standards at contributing laboratories and also
> earth rotation measurements. Each lab contributing will at any time (excuse
> the pun) have a small time offset with regard to UTC. E.g. time from NPL in
> UK would say be offset from UTC at any time by a few microseconds, and would
> be designated UTC-NPL. Worth reading
> Interestingly there is a lot of research into more stable clocks using
> Mercury and Ytterbium. This then leads to discussion about a future possible
> re-definition of the second (which IMHO will happen).
Yes... At JPL there's work going on with a linear trapped Hg ion clock for
spacecraft. Stability is 1E-12/sqrt(tau), with temperature sensitivity on
the order of 1E-15/degree (at the basic sensor). Roughly a liter in volume
and 1 kg. When it's done, it will enable a lot of changes in things like
navigating spacecraft and making precise measurements over long distances.
(because you can do one-way measurements, as opposed to two way)
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