We report the result of the analysis of a dramatic repeating
gravitational microlensing event OGLE-2009-BLG-092/MOA-2009-BLG-137, for
which the light curve is characterized by two distinct peaks with
perturbations near both peaks. We find that the event is produced by the
passage of the source trajectory over the central perturbation regions
associated with the individual components of a wide-separation binary.
The event is special in the sense that the second perturbation,
occurring ~100 days after the first, was predicted by the real-time
analysis conducted after the first peak, demonstrating that real-time
modeling can be routinely done for binary and planetary events. With the
data obtained from follow-up observations covering the second peak, we
are able to uniquely determine the physical parameters of the lens
system. We find that the event occurred on a bulge clump giant and it
was produced by a binary lens composed of a K- and M-type main-sequence
stars. The estimated masses of the binary components are M 1
= 0.69 ± 0.11 M sun and M 2 = 0.36 ±
0.06 M sun, respectively, and they are separated in
projection by r bottom = 10.9 ± 1.3 AU. The measured
distance to the lens is D L = 5.6 ± 0.7 kpc. We also
detect the orbital motion of the lens system.
