Upper panel: filter configuration used in this study, shown on an LBG simulated spectrum at z = 3.78 (see Section 3.1 for the simulated spectrum details). The NBs were designed specially for this program to identify LBGs at ﹩z\sim 3.78﹩ by detecting the Lyα break. This filter configuration selects galaxies in a quiet narrow redshift slice of ﹩{\rm{\Delta }}z\sim 0.3﹩. Lower panel: example of a filter set used to identify galaxies with the standard Lyman break technique that is based in the detection of the Lyman limit break. The filter curves shown are those used by Ouchi et al. (2004a) to find LBGs at z ∼ 4 over a redshift slice of ﹩{\rm{\Delta }}z\sim 1.0﹩.