Post-post-Newtonian deflection of light by the Sun

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Abstract
Using a generalized metric, we calculate the post-post-Newtonian (ppN) contribution to the deflection of starlight by the Sun as well as the post-Newtonian deflections due to the Sun's gravitational quadrupole moment and angular momentum. For light rays grazing the Sun, the magnitudes of these deflections predicted by general relativity are, respectively, about 11, 0.2, and 0.7 μ arcsec. A covariance analysis shows that the ppN contribution could be measured with an uncertainty under 20% with an optical interferometer, in Earth orbit, that can determine the separation of stars with an uncertainty of 1 μ arcsec.