Clustering of Red Galaxies near the Radio-loud Quasar 1335.8+2834 at [CLC][ITAL]z[/ITAL][/CLC] = 1.1

We have obtained new deep optical and near-infrared images of the field ofthe radio-loud quasar 1335.8+2834 at $z=1.086$ where an excess in the surfacenumber density of galaxies was reported by Hutchings et al. [AJ, 106, 1324]from optical data. We found a significant clustering of objects with very redoptical-near infrared colors, $4 \lesssim R-K \lesssim 6$ and $3 \lesssim I-K\lesssim 5$ near the quasar. The colors and magnitudes of the reddest objectsare consistent with those of old (12 Gyr old at z=0) passively-evolvingelliptical galaxies seen at $z=1.1$, clearly defining a `red envelope' likethat found in galaxy clusters at similar or lower redshifts. This evidencestrongly suggests that the quasar resides in a moderately-rich cluster ofgalaxies (richness-class $\geq 0$). There is also a relatively large fractionof objects with moderately red colors ($3.5 < R-K < 4.5$) which have adistribution on the sky similar to that of the reddest objects. They may beinterpreted as cluster galaxies with some recent or on-going star formation.Comment: 14 pages text, 5 PostScript figures, 1 GIF figure, and 1 combined PS file. Accepted for ApJ, Letter