Series of smoothed slice plots with thickness 2 h ⁻¹ Mpc (150.095 < R.A. < 150.125) that include the COSTCO-I galaxy protocluster, which is marked with a star. From top to bottom, the panels show the transmission of CLAMATO, the density contrast of one COSTCO-constrained simulation, the transmission of the corresponding COSTCO-FGPA Lyα forest mock, and the mean Lyα transmission averaged over all realizations. The abscissa (x-axis) is along the LOS dimension, while the ordinate (z-axis) is along increasing decl. in the transverse plane. All of the maps are smoothed with a 4 h ⁻¹ Mpc Gaussian kernel, while the circles indicate the r = 15 h ⁻¹ Mpc sphere over which we average in Section 3.2. In addition, we mark with dashed circles two other extended structures around the COSTCO-III (at z = 2.18) and CC2.2 (at z = 2.22) protoclusters, even though their barycenters are outside the plane of the slices shown here.