Image of spectral PSF subtraction to remove the light from the central unresolved emission component at 4450 Å. The maximal point source contribution is subtracted to create a hole in the middle of the spatial profile of the emission line. Even after this conservative procedure, a clear, extended component on either side of the quasar trace is denoted with a dotted line. These properties make the interpretation of this line as Lyman-α most likely compared to alternative explanations involving the superposition of two unrelated objects on the slit.