[time-nuts] Valentines Day & Love Numbers

Brooke Clarke 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?

Have Fun,

Brooke Clarke

More information about the time-nuts mailing list