Distributions of the best-fit wavelength λ_0;est (left panels; cumulative) and flux f_0;est (right panels) for input spectra with an emission line at the effective wavelength (top panels) and at 50% transmittance (bottom panels) of the two NB118 filters’ combined passband. In each panel, distributions are shown for five different Ha fluxes. The respective values are listed in the legend in units of ergs^-1cm^-2. The input EW_obs;in was 10 nm in all five cases. Fits were obtained at both transmittances for 500 realizations of simulated observations in NB118 14 and 15, Y, J, and H. Dashed lines indicate that the objects would not be selected as NB excess objects.