Hδ (dashed lines) and H6 (solid lines) equivalent widths as a function of stellar-population age, for BC03 SSP models smoothed to 9 Å resolution. Note that the H6 equivalent width begins to rise at intermediate ages due to the influence of the CN band, while Hδ continues to fall with age after a peak around 300 Myr. The vertical black dashed and dotted lines represent the ages of the universe at the redshifts of J1252.9 and J0152.7, respectively.