Four examples of detections present in the group catalog, at different redshifts. Circles indicate member galaxies, color-coded with membership probability and with their redshift printed next to each circle. Purple-to-yellow contours mark the density of galaxies and green contours the X-ray emission from the combined XMM-Newton and Chandra mosaic image in the 0.5−2 keV band. White lines delimit masked areas. The center of the group is marked with a red cross. In the top left panel, a group at z = 0.71 with λ_⋆ ∼ 78 and central AGN (the same group shown in Fig. 1). In the top right panel, a group at z = 1.29 with λ_⋆ ∼ 14. In the bottom left panel, a group at z = 2.22 with λ_⋆ ∼ 24 and on the bottom right panel one at z = 3.14 with λ_⋆ ∼ 28, flagged for being on the extended X-ray emission of a low-z group and for being at the edge of the field, as visible on the top of the stamp. JWST rgb images are in the same filters as in Fig. 1.