Illustration of the flux calibration procedure. Top: in blue, extracted standard star spectrum in pseudo-ADU of BD+33d2642; in orange, flux-calibrated CalSpec spectrum of the same star convolved at the SEDM wavelength resolution used as flux reference. Bottom: in black, ratio between CalSpec and SEDM spectra (top). The green curve is the full flux calibration model (continuum+telluric). The influence of the telluric correction is shown as a gray shaded area; hence the lower of the gray area represents the continuum component of the flux calibration. When flux-calibrating a science target, the intensity of the telluric component (in gray) varies to match that expected at the science target air-mass.