Left: (z − 3.6  μm) color−magnitude relation of CXO1415. Only objects within 1′ distance from the X-ray center are shown (black circles). The 21 red cluster candidates (red circles) are selected on the basis of the color cut 5 < z − 3.6  μm < 6.5. For comparison we also plot 19 confirmed members of WARPJ1415 at z = 1 (blue triangles). The magenta star indicates the galaxy coincident with the X-ray peak. Right: selection of red, high-z cluster galaxy candidates (white circles), with X-ray contours displayed in green. The brightest candidate is marked by a yellow circle.