Caustics around a 1 M_⊙ microlens on the side with negative parity at the redshift of the cluster lensing a background source at z = 2.091. The macromodel magnification in this region is ≈850, and the gray scale indicates the combined magnification μ of the macromodel and the microlens. The black horizontal band corresponds to the demagnification region that exists only for images with negative parity. The microlens can demagnify a lensed star down to μ ≈ 10 in this band. Lighter triangular regions above and below show high-magnification regions. The yellow horizontal line illustrates a trajectory grazing the bottom horizontal caustic, and the black line is for a trajectory 0.1 μas south of the yellow line. These lines correspond to the yellow and black curves in Fig. 9.