[time-nuts] Eclipse alert - Call for VCO traces

[Magnus Danielson]

iovane at inwind.it wrote:
> Time-nuts,
> 
> many of you are routinely recording - or may easily do it - the 
> trace 
> of the control voltage of non-free-running crystal oscillators 
> 
> (disciplined by atomic resonance or GPS).
> 
> Once again I'm here asking you to 
> keep an open eye during a solar 
> eclipse, which will occur on January 15. 

For meaningfull measurement shall the temperature shall be logged as well.

> My current opinion is that the eclipse couldn't affect atomic 
> resonances at a 
> measurable level for the state of the art, but could 
> affect massive (as 
> compared to atoms) pieces of vibrating matter. 

Well, it has been established that they do affect atomic clocks onboard 
GPS satellites and that this can be correlated to the clocks temperature 
dependencies. Improved temperature compensations on modern rubidiums 
flown has reduced this efffect to the best of my knowledge. Rubidiums 
have a temperature dependence due to their traditional design, but this 
can be reduced by design and by compensation.

> The control voltage trace tells us whether a crystal deviated, even in 
> front of a constant rate of the whole clock. 
> 
> I recall (already mentioned in this list) that previous tests 
> (Max Plank Institute) showed no deviations of atomic resonances, but we 
> don't have info about control voltages, and that S.W.Zhou instead 
> claimed to have observed deviations that indeed I believe were 
> deviations of crystals not promptly steered.

Tossing the same clock into a climate chamber and test the temperature 
dependence would be interesting.

> During this eclipse a numerous team of researchers will be conducting
> sophisticated pendulum tests at the Maldives (latitude near to zero, 
> no Foucault effect), and a number of US institutions, located in the 
> anti-eclipse path, will provide gravimeter data. Elsewhere, Russia and 
> Florida at least, torsion balance tests will be conducted. Just to
> mention what I'm aware of.
> 
> As far as I know, nobody will provide clock (I would say oscillator)  
> data. Hence I' m asking this list to give a contribution. 

Make sure to separate temperature effects from that of any other effect, 
such as gravitational.

> What I ask is to send me your control voltage data, possibly for the 
> days 14-15-16 January, and from preferred locations -but not only- in 
> the eclipse or anti-eclipse path, even penumbra or anti-penumbra. 

T-bolt and Z-3801 owners with the correct software should be able to 
deliver suitable data.

Cheers,
Magnus