and $I$ brightnesses with the same magnitude zero-points as for the images of the core, but avoided adding the color corrections, because we did not have ground-based estimates. We found $R_{\rm arc} = 24.3 \pm 0.3$, $I_{\rm arc} = 23.0 \pm 0.2$ and, hence, $R_{\rm arc}-I_{\rm arc} = 1.3 \pm 0.3$ mag and $R_{\rm core}-I_{\rm core} = 2.2 \pm 0.1$ mag; hence the arc is significantly (2$\sigma$ level) bluer than the QSO core. We also subdivided our aperture into 4 equal, independent, adjacent rectangular apertures, to estimate color variation along the arc. We found no variation, within the standard error of 0.3 mag in our measurements.

We attempted to improve the resolution of our combined images by deconvolution of the PSF in each band, to explore qualitative features of the images. We calculated PSFs appropriate to each band and to PC1 with Tiny Tim v. 4.0 (Krist 1996). Figure 5 shows the results of MEM deconvolution with these PSFs. The deconvolved brightness levels are shown as a contour plot for the $R$ image, where the arc stands out most clearly. This figure shows that the images of the core were sharpened to point-like sources. The longer segment of the arc 