[time-nuts] Result of Earth Quake speeds up earth?

[Chris Albertson]

Does anyone here know the current state of the art for timing the
Earth's rotation?    I know the outline, An instrument on a transit
telescope notes the time when a star passes overhead.  You take many
of these observations and you can determine the period

What is the instrument of choice?   Is it still a transit telescope or
do that track a star's motion over a longer span of time?  I'd guess
that getting a good rotational period would required tracking many
stars over months and years.

What about effects like parallax due to the Earth's orbit around the
sun,?  Do they only use very distant stars?  Or do they use radio
telescopes now.

If I were doing this in my backyard on a budget I'd mount a small
telescope nearly straight up so that a bright star would pass through
the field on several nights.  I'd measure the light of the star
through a slit and time the peak of the light each night.  I bet I
could get to about a microsecond.   I'm wondering what professionals
are doing in this field.


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Chris Albertson
Redondo Beach, California