[time-nuts] Valentines Day & Love Numbers
brooke at pacific.net
Wed Feb 19 13:24:19 EST 2014
In the video about the Full Moon Curse (that's about measuring the distance to each of the 5 retro-reflectors on the
moon to 1 mm) there's a plot showing the elevation change in the Apache Point Observatory of about 20 inches peak to
peak. It's exactly the type of change the effects pendulum clocks.
I asked Tom Murphy if he used GPS to get the elevation plot and the answer is that it came from the gravitymeter with
the use of Love numbers.
http://en.wikipedia.org/wiki/Love_number <- has links to papers on Earth tides
Also see patent 3449956 and GWR instrument link at:
This means that the concrete piers where many Cesium clocks and GPS reference stations are located are bobbing up and
down as if they were on a ocean, although only tens of inches.
I think there was an earlier post saying this puts a limit (E-16?) on the ultimate quality of a clock because of it's
movement. I wonder if NIST has one of the GWR gravitymeters on a pier and uses that to discipline their fountain clocks
for the elevation change of the pier or if that's done for the GPS reference antennas?
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