The Naval Observatory and others have been doing this for years albeit
averaged over several observations and by fitting curves to the stellar
transit path in the transit circle focal plane eg:
http://adsabs.harvard.edu/full/1986IAUS..109..483H
The setup with Heidenhain elevation encoders etc was impressive when I
visited the facility in the 1980's.
The accomodation etc was in stark contrast to the Observatory a little
further up the hill where we only had underfloor heating and didnt
obseve from the comfort of a temperature controlled computer room.
Bruce
Brooke Clarke wrote:
Hi Bruce:
From what I can learn about "seeing" the atmosphere instability is too
great to allow making measurements optically in the 1 ms area.
It's a couple of acres.
Have Fun,
Brooke Clarke
http://www.PRC68.com
Bruce Griffiths wrote:
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
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