NSF Absolute Gravity

An absolute gravity meter measures the acceleration of gravity
directly by observing the free-fall of a reflective corner
cube in a vacuum. Position is measured with an iodine laser and
time with an atomic clock. The value for g is thus determined in 
terms of atomic constants that are assumed stable over periods of
centuries. This is in contrast to a spring-based relative
meters which observe gravity differences  in time or place. The
current FG5 meter is the fifth in a series of designs of
absolute meters developed with the guidance of James Faller (JILA). In 1994
the National Science Foundation (NSF) with matching funds from 
the University of Colorado purchased an absolute gravity meter 
(FG5-111). This instrument is available to university investigators 
on request.
How does the FG5 absolute-g instrument operate?
How accurate is it?
Data 1995-1998
Useage in Geophysics (g) and Physics (G)
Where is it maintained?
FG5 investigators instruction manual
Bibliography on absolute-g measurement.
Workshop Report 1993

for further information email
bilham at colorado.edu