[time-nuts] Re: LTC

[Bob Camp]

Hi

The only real issue here is *if* your time source is on the moon, it will need to
tune far enough to stay locked up. For an OCXO based gizmo, not a big deal. 
For something more exotic, the tuning range might or might not be adequate on
an “out of the box” device. I sort of doubt that anybody seriously is thinking about
grabbing a “stock” fountain clock and just shooting it off to the moon …..

Bob

> On Apr 12, 2024, at 3:20 PM, Attila Kinali via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> On Fri, 12 Apr 2024 12:09:26 -0700
> Hal Murray <halmurray at sonic.net> wrote:
> 
>> Attila Kinali said:
>>> I guess the "off by 58.7µs" is just someone incorrectly stating the
>>> difference in relativistic shifts between a clock running on earth and on the
>>> moon.
>> 
>> What do people on Earth do if they live in someplace like Denver that isn't at 
>> sea level.
> 
> We do correct for gravitational redshift already.
> 
> Until recently, a simple using the simple geo-potential survey
> we had, was enough. The gravitational redshift on earth is
> approximately 1.1e-16/m. It hasn't been very long that the
> uncertainties in the realization of the second got below 1e-15.
> So, an uncertainty in the geopotential of a few meters was ok.
> 
> I know that in the last decade quite a few labs measured their
> local gravitational potential. But I guess, with the upcoming
> redefinition of the second, the proliferation of optical
> clocks, and the progress we had in gravitational sensors
> (quite a few of them coming out of SYRTE in Paris), there is
> likely to be a new campaign to measure gravitational potentials
> more accurately again, in the next decade.
> 
> 
> 			Attila Kinali
> -- 
> The driving force behind research is the question: "Why?"
> There are things we don't understand and things we always 
> wonder about. And that's why we do research.
> 		-- Kobayashi Makoto
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