Spitzer Observations of OGLE-2015-BLG-1212 Reveal a New Path to Breaking   Strong Microlens Degeneracies
  Spitzer microlensing parallax observations of OGLE-2015-BLG-1212 decisively breaks a degeneracy between planetary and binary solutions that is somewhat ambiguous when only ground-based data are considered. Only eight viable models survive out of an initial set of 32 local minima in the parameter space. These models clearly indicate that the lens is a stellar binary system possibly located within the bulge of our Galaxy, ruling out the planetary alternative. We argue that several types of discrete degeneracies can be broken via such space-based parallax observations. 
V. Bozza, Y. Shvartzvald, A. Udalski, S. Calchi Novati, I.A. Bond, C.   Han, M. Hundertmark, R. Poleski, M. Pawlak, M. K. Sz...
astro-ph.EP