General relativistic corrections to the Sagnac effect
  The difference in travel time of corotating and counter-rotating light waves in the field of a central massive and spinning body is studied. The corrections to the special relativistic formula are worked out in a Kerr field. Estimation of numeric values for the Earth and satellites in orbit around it show that a direct measurement is in the order of concrete possibilities. 
A. Tartaglia (Dip. Fisica, Politecnico, Torino, Italy)