We present a new analysis of the Jupiter+Saturn analog system, OGLE-2006-BLG-109Lb,c, which was the first double planet system discovered with the gravitational microlensing method. This is the only multi-planet system discovered by any method with measured masses for the star and both planets. In addition to the signatures of two planets, this event also exhibits a microlensing parallax signature and finite source effects that provide a direct measure of the masses of the star and planets, and the expected brightness of the host star is confirmed by Keck AO imaging, yieldingThe Saturnanalog planet in this system had a planetary light curve deviation that lasted for 11 -3days, and as a result, the effects of the orbital motion are visible in the microlensing light curve. We find that four of the six orbital parameters are tightly constrained and that a fifth parameter, the orbital acceleration, is weakly constrained. No orbital information is available for the Jupiter-analog planet, but its presence helps to constrain the orbital motion of the Saturn-analog planet. Assuming co-planar orbits, we find an orbital eccentricity of = 0.15 +0.17 −0.10 and an orbital inclination of i = 64 • +4 • −7 • . The 95% confidence level lower limit on the inclination of i > 49 • implies that this planetary system can be detected and studied via radial velocity measurements using a telescope of > ∼ 30 m aperture.

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