In this paper , we present the analysis of the binary gravitational microlensing event OGLE-2015-BLG-0196 .
The event lasted for almost a year and the light curve exhibited significant deviations from the lensing model based on the rectilinear lens-source relative motion , enabling us to measure the microlens parallax .
The ground-based microlens parallax is confirmed by the data obtained from space-based microlens observations using the Spitzer telescope .
By additionally measuring the angular Einstein radius from the analysis of the resolved caustic crossing , the physical parameters of the lens are determined up to the two-fold degeneracy : u _ { 0 } < 0 and u _ { 0 } > 0 solutions caused by the well-known “ ecliptic ” degeneracy .
It is found that the binary lens is composed of two M dwarf stars with similar masses M _ { 1 } = 0.38 \pm 0.04 M _ { \odot } ( 0.50 \pm 0.05 M _ { \odot } ) and M _ { 2 } = 0.38 \pm 0.04 M _ { \odot } ( 0.55 \pm 0.06 M _ { \odot } ) and the distance to the lens is D _ { L } = 2.77 \pm 0.23 kpc ( 3.30 \pm 0.29 kpc ) .
Here the physical parameters out and in the parenthesis are for the u _ { 0 } < 0 and u _ { 0 } > 0 solutions , respectively .