[time-nuts] Result of Earth Quake speeds up earth?

[cook michael]

Le 20/03/2011 05:59, Bruce Griffiths a écrit :
>
> jimlux wrote:
>>
>>>
>>> A 10-12m diameter dish is probably close to the minimum feasible 
>>> aperture.
>>> A 4m dish can be made to work in conjunction with a mauch larger dish
>>> (eg 30m).
>>>
>>
>> The original speculation was for measuring the small change in earth 
>> rotation rate, for which some sort of interferometric measurement of 
>> a stellar source could be used.

I sincerely doubt that it will be possible to get undisputed 
verification of this speed up as the magnitude is swamped by the 
irregular diurnal and sub-diurnal rotation rates induced by tidal 
effects that are at lease a magnitude greater and for which the error 
bars are of the same order or grater than the predicted shift.

There was a similarly predicted rotation shift predicted for the Chile 
quake of 28 February 2010 (1,26us). There was IIRC no verification of 
that AFAIK. Check the tidal effects at

http://bowie.gsfc.nasa.gov/ggfc/tides/intro.html  for the tidal effect
and
http://hpiers.obspm.fr/     for rotational measured speed changes
http://hpiers.obspm.fr/eop-pc/index.php?index=news    for the statement 
of detectability.





>>
>> The source has to be bright (so you can detect it with a practical 
>> antenna.. not everyone has a 30m dish in their back yard)
>> The source has to be small angle (or at least something that you 
>> could accurately determine the centroid of)
>> The source has to be "not moving"  (which I think leaves out using 
>> something like jupiter)
>> The frequency of measurement has to be somewhere that the atmosphere 
>> won't dominate the uncertainty (leaving out optical, I think)
>>
>>
>> SO what's the brightest small angular radio source out there?
>
> 3C273
>
> RA 12:29.1 DEC 02:03.1
>
>>
>>
>> As someone else has pointed out, measuring the earth surface position 
>> relative to spacecraft orbits, e.g. GPS, would be another technique.  
>> In fact, a high resolution measurement of the position of a geosync 
>> sat might do.. If the earth's rotation rate changes you'd have to 
>> adjust the height of the satellites in Clarke orbit to keep them 
>> stationary.
>>
>> Unfortunately, for earth orbiters, there's enough other perturbations 
>> that you probably can't see it.  They already have to move satellites 
>> around to compensate for things like solar wind, air drag (for LEO), 
>> etc.
>>
>> But maybe for a spacecraft in deep space, between planets, which is 
>> on a well understood trajectory?
>>
>>
> Bruce
>
>
>
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