[time-nuts] Primary Time Standards

[Magnus Danielson]

On 14/07/11 18:56, Bob Camp wrote:
> Hi
>
> One would assume that mean sea level / 1 G would be the standard reference
> point for the "official" Cs transition. I've never seen anybody pull out a
> gravity meter to set up their Cs though. I suspect that NIST has at least
> done the math.

The gravity may be ignored when comparing clocks within the same lab, 
unless with very stable clocks, in which case they either need to be 
brought to the same level or compensation needs to be done.

However, the gravitational differences is being compensated nowdays as 
TAI is being calculated.

If you read the fine-print, the SI second is now defined for sea-level 
gravity and at 0 K black-body raditation, so compensation for these 
effects should be done.

Cheers,
Magnus