[time-nuts] BYMLBI (Back Yard Medium LBI)

[Bruce Griffiths]

Brooke Clarke wrote:
> Hi:
>
> For a number of decades I've tried to figure out a way to measure the 
> period of the Earth's rotation accurate to at least 1 ms.
> For some thoughts (since I don't think it will work) on doing it 
> optically see:
> http://www.prc68.com/I/StellarTime.shtml
>
> Is it possible to do it using a radio method in my (large) back yard?
>

1ms corresponds to an angle of 15 milliarcsec or 73 nrad for 0 
declination objects.

15 milliarc sec positioning accuracy is just within the capability of an 
7" aperture transit circle or PZT equipped with a CCD camera.
This accuracy was close to that achievable with a video camera equipped 
transit circle in the late 1980's.

A 2900 km diameter dish or equivalent has a resolution of about 73 nrad 
at 1420MHz.
Position accuracy for a point source can be somewhat higher than the 
resolution if the SNR is sufficiently high.
However an antenna system of several hundred km in extent is likely to 
be necessary.

Just how large is your backyard?

Bruce