TITLE: GCN CIRCULAR NUMBER: 6195 SUBJECT: GRB 070311: MDM Optical Detection DATE: 07/03/11 19:03:12 GMT FROM: Jules Halpern at Columbia U. J. P. Halpern & E. Armstrong (Columbia U.) report on behalf of the MDM Observatory GRB follow-up team. "We acquired R-band observations of INTEGRAL GRB 070311 (Mereghetti et al., GCN 6189) using the MDM 1.3m telescope on Mar. 11 02:44-03:28 UT. The IR afterglow discovered by Covino et al. (GCN 6190) and confirmed by Bloom (GCN 6191) is well detected in our images. In an uncalibrated image, we measure a preliminary magnitude of R = 21.12 +/- 0.09 at a mean time of 02:47 UT, or 54 minutes post-burst. This is with respect to a comparison star with USNO-B1.0 magnitude R2=16.67 at (J2000) 05:50:11.83, +03:22:25.2. This message may be cited"