Left panel: 1D spectrum of the AzTEC-3+LBG-3 system in the Lyα wavelength range. The original-sampling spectrum is shown in blue with error bars, the one smoothed by 3 × 3 wavelength channels in black. The error spectrum comes from the rescaled variance cube. The magenta spectrum is the theoretical sky spectrum from Rousselot et al. (2000) in arbitrary units. Right panels: same as the left panel for LBG-1.