Ice maps. In these images, a projection along the Z-axis, resulting in a line-of-sight column (cm^-2), is plotted within a 16 × 16 pc box. From top left to bottom right, ice maps of the species ⊥H₂O, ⊥CO, ⊥H₂CO, and ⊥CH₃OH are displayed. The color range representing the species column densities spans from low 10¹⁰ (black) cm^-2 to high 10²⁰ cm^-2 (red) values. The contours enclose the region where the total column density, , ranges from 10²² to 6 × 10²² cm^-2, i.e., A_V = 4.5−27, to indicate where most of the matter lies.