[time-nuts] Primary Time Standards

[J. Forster]

No. The standards of time interval are atomic, not linked to the Earth's
rotation. Hence Leap Seconds.

-John

==============



> Jim,
>
> It is my understanding that the government standard offices around the
> globe, like NIST, calculates time by the earths rotation, I guess you
> could
> say, the old way, or using astronomy, but with this, they use things like
> the decay factors of atomic materials to keep this time. If I recall,
> things had to be recallibrated after the earthquake at Japan, as it
> changed
> the earths rotational speed a very minute amount. Its kind of like, which
> came first, the chicken or the egg on the standards.
>
> Best,
>
> Will
>
> *********** REPLY SEPARATOR  ***********
>
> On 7/14/2011 at 12:26 PM Jim Palfreyman wrote:
>
>>Hi All,
>>
>>I've just realised I don't understand something. Something quite basic.
>>
>>Primary Standards are ones which don't have to be calibrated against
> others.
>>My understanding is that Caesium and Hydrogen masers are Primary
>> Standards
>>(in our field).
>>
>>Secondary Standards are calibrated against the Primary Standards. My
>>understanding is that Rubidium is an example of a Secondary Standard.
>>
>>So I can calibrate my Rubidium clocks by adjusting the C Field. All good.
>>
>>But why is it that Caesium Clocks and Hydrogen Masers have an adjustment
>>facility?
>>
>>And what about the clocks used to determine UTC around the world? Do they
>>have an adjustment facility? What are they adjusted to? Wouldn't that
>> make
>>them Secondary Standards?
>>
>>Now I'm aware that the "average" of those clocks is UTC, so are those
> clocks
>>adjusted regularly to get closer to that average?
>>
>>I'm sure someone can clear this up for me.
>>
>>Regards,
>>
>>Jim
>>_______________________________________________
>>time-nuts mailing list -- time-nuts at febo.com
>>To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>and follow the instructions there.
>>
>>__________ Information from ESET Smart Security, version of virus
> signature database 5851 (20110206) __________
>>
>>The message was checked by ESET Smart Security.
>>
>>http://www.eset.com
>
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>