Relative differences, in percent, between the response curves found on different nights for the V500 grating dataset (top panel) and the V1200 grating (bottom panel), as a function of wavelength, normalized to unity at 4600 Å and 4150 Å, respectively. The solid hashed region (and red solid line) shows the 1σ error, while the dashed hashed region (and black dashed line) shows the 2σ error.