Δχ² map in (log s, log q) parameter space for OGLE-2016-BLG-1609. We named the three visible topologies according to the projected separation: inner-large q (labeled A and delineated by the dashed blue line), small q (B, dot-dashed orange line), and outer-large q (C, dotted green line). Crosses mark the lowest-χ² models for each topology, and boxes represent the s and q limits used in modeling.