Colour-colour F277W-F356W vs F200W-F277W (top) and F277W-F356W vs F356W-F444W (bottom) diagram of the HELM samples. The shaded grey area and the dashed black lines are the golden and silver selection criteria for z = 15 − 20 (top) and z = 20 − 30 (bottom) by Castellano et al. (2025). We show only HELM galaxies with S/N > 3 in the considered filters. Median errors are reported in the top right of the plot.