The equivalent width W_DIB as a function of foreground extinction A_V. Small points are the individual sightline measurements, with the color indicating the mean extinction per kpc along each sightline toward the background star. The larger white circles are the W_DIB medians in each Δlog A_V = 0.04 bin, along with the uncertainty in the median, and the gray line is the fitted W_DIB/A_V relationship. Note that at low A_V, a large fraction of the uncertainty is coming from the extinction measurement, rather than the DIB equivalent width.