Distribution of rest-frame wavelengths for the spectroscopically confirmed NB candidates. The top panel shows a zoomed-in view on the wavelength range around Hα . We also show the transmission profiles of the nine NB filters used to select the Hα candidates, converted to the Hα rest-frame (thin gray lines). We confirm the majority of NB candidates (>70%) as Hα emitters at the cluster redshifts, with the rest confirmed as either stars or galaxies at other redshifts.