[LEAPSECS] the abbreviation UTC

[mike cook]

Le 18/08/2011 14:06, Gerard Ashton a écrit :

>

> On 8/18/2011 4:30 AM, mike cook wrote:

>

>     Could this be a good argument for getting parking ticket offences 

> thrown out?

>

> Under current rules, UTC is an approximation to mean solar time at 

> some meridian that passes through the grounds of the Royal 

> Observatory, Greenwich (although not necessarily the crosshair of the 

> Airy Transit Circle). The wristwatch of the traffic enforcement 

> officer is an approximation to the mean solar time that is in force as 

> civil time in the UK. Ignoring differences of one hour due to summer 

> time, the difference between UTC and the civil time is probably less 

> than one second. (It is less than 0.9 s between UT1 and UTC, and I 

> would guess the various variations in the plausible locations of the 

> meridian and the various algorithms for computing mean time would be 

> less than 0.1 s.) As a rule of thumb, higher accuracy standard should 

> have a tolerance of 1/3 of a lower accuracy standard that is to be 

> calibrated. Thus, if there is an uncertainty of +/- 1 s in the meaning 

> of GMT, the traffic enforcement officer's wristwatch may still be 

> calibrated with UTC provided the wristwatch need not have an accuracy 

> of better than +/- 3s.

>

> I would be most surprised if there is an actual written procedure that 

> traffic officers must follow in setting their wristwatches and a 

> specified grace period officers must allow before issuing a citation, 

> but maybe the officers in the UK are better organized than the ones 

> I've encountered in the USA.

>

My argument is not that the lawmans watch is not to any particular 
accuracy , but that it might be showing some value ( time ) that has no 
legal existence. Lawyers like that stuff. A good example is with 
Parisian parking meters. It is written in law that anyone selling 
anything must accept  legally accepted currency .Parisian parking meters 
don't accept notes, and the current ones don't even accept coins, having 
been swapped with prepaid card or credit card affairs due to robbers 
sawing them off at the base to rip off the takings.   So you can have 
your parking offence canceled by writing Prefect of police to that effect.


> Gerry Ashton

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