Galactic microlensing with rotating binaries

The influence of rotating binary systems on the light curves of galactic microlensing events is studied. Three different rotating binary systems are discussed: a rotating binary lens, a rotating binary source, and the motion of the earth around the sun (parallax effect). The most dramatic effects arise from the motion of a binary lens because of the changes of the caustic structure with time. I discuss when the treatment of a microlensing event with a static binary model is appropriate. It is shown that additional constraints on the unknown physical quantities of the lens system arise from a fit with a rotating binary lens as well as from the earth-around-sun motion. For the DUO#2 event, a fit with a rotating binary lens is presented