Distribution of near-infrared sources toward PLCK_G165.7+49.0, including candidate members of the foreground structure. The grayscale shows the CFHT K_s-band image and blue contours indicate local overdensities from the adaptive kernel density estimate, from 1 to 6σ. A main peak at 6.4σ near the Emerald and two secondary peaks at > 4σ are found (blue triangles), indicating a particularly rich environment. The position of the Emerald (the submm arc) is shown as a white diamond. Red and yellow circles indicate galaxies that fall onto the red sequence, or have photometric redshifts consistent at the 2σ level with z = 0.35, respectively. The three galaxies marked G1, G2 and G3 have spectroscopic redshifts around z = 0.35 available in the SDSS, as reported in Table 1. We show the 5′ × 5′ field-of-view used to characterize the foreground mass distribution. North is up and east is to the left.