Stacked difference , where α_i was chosen to minimize the contribution from the arc to the difference, and FnnnW_i are all filters with wavelengths below 2 μm, that is F090W, F115W, and F150W. These were degraded to the resolution of F200W using the star-derived PSF in Appendix B. The individual differences are shown in Col. 3 of Fig. B.2. The stacked image has been smoothed with a Gaussian of to increase the contrast. The position of LS1 is marked with a white arrow. The position of the possible counterimage LS1′, ≈01 from LS1, is marked with a yellow circle.