Top panel: the characteristic magnitude as a function of redshift used in Eq. (1). Note that the J band magnitudes are used in the redshift range 1 < z < 1.5 and the K_s band magnitudes are used at 1.5 < z < 2.0. Middle panel: median photometric redshift errors of galaxies in the magnitude range as a function of redshift for the D1 (solid line) and D4 (dashed line) fields. Bottom panel: the photometric redshift distribution of galaxies in the K_s selected catalogue with magnitudes of .