Color–magnitude relation. The i₇₇₅ − z₈₅₀ (upper panel) and the z₈₅₀ − H₁₆₀ (lower panel) colors of the selected ETGs galaxies (red filled symbols) as a function of z₈₅₀ (16 galaxies) and of H₁₆₀ (15 galaxies) are shown together with those of the 105 galaxies (black crosses) covered by NICMOS observations. The five ETGs with spectroscopic redshift are marked by red filled circles and the remaining 11 ETGs cluster members are marked by red filled triangles. Red open circles mark all the galaxies selected in the color range 0.9 < i₇₇₅ − z₈₅₀ < 1.3. The solid red line in the upper panel is the color–magnitude relation (i₇₇₅ − z₈₅₀) = 2.1 − 0.044z₈₅₀ best-fitting the 16 ellipticals.