Mean transmission, , calculated using the DR12 pipeline of our previous investigations, and using the DR13 pipeline applied to DR12 data of this analysis. The DR13 pipeline allows us to divide forest spectra by the correction factor (Fig. 4) derived from the spectra on the red side of Lyα emission. This procedure eliminates most of the small scale structure found with the old pipeline that is due to artifacts of stellar modeling, Galactic calcium H and K absorption, and sky lines.