Multicolor photometry of the J0053+1234 field. ﹩U-B﹩ vs. ﹩R-I﹩ color‐color plot for the 1552 sources with UBRI photometry. The photometry presented here has been corrected for air mass and color terms, as well as Galactic extinction using the Schlegel et al. (1998) reddening maps. The mean systematic color errors, which dominate over random photometric errors, are given in box at the lower left. A cut of ﹩B< 21.3﹩ is applied to keep random photometric errors low enough that the stellar locus is well‐defined. As in Fig. 2, the 44 spectroscopically confirmed quasars (filled triangles) and 48 confirmed non‐quasistellar objects (open triangles) are shown. We show the ﹩U-B\leq -0.2﹩ (solid line) and ﹩U-B\leq -0.1﹩ (dashed line) boundaries.