Due to the high efficiency of planet detections, current microlensing planetsearches focus on high-magnification events. High-magnification events aresensitive to remote binary companions as well and thus a sample ofwide-separation binaries are expected to be collected as a byproduct. In thispaper, we show that characterizing binaries for a portion of this sample willbe difficult due to the degeneracy of the binary-lensing parameters. Thisdegeneracy arises because the perturbation induced by the binary companion iswell approximated by the Chang-Refsdal lensing for binaries with separationsgreater than a certain limit. For binaries composed of equal mass lenses, wefind that the lens binarity can be noticed up to the separations of $\sim 60$times of the Einstein radius corresponding to the mass of each lens. Amongthese binaries, however, we find that the lensing parameters can be determinedonly for a portion of binaries with separations less than $\sim 20$ times ofthe Einstein radius.
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