Example of the straylight subtraction process. Top panel: pixel counts along a CCD cross-dispersion cut of the science observation. A sixth order polynomial fit only through the gaps between the fiber bundles is shown as the red line. Bottom panel: straylight maps for the V500 and V1200 data, respectively, reconstructed from the polynomial fit for each cross-dispersion slice of the CCD and smoothed by a 2D Gaussian filter with a 20 pixel width.