TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3530 SUBJECT: GRB 050607: MDM Observations DATE: 05/06/07 17:51:25 GMT FROM: Jules Halpern at Columbia U. J. P. Halpern (Columbia), J. Kemp (Joint Astronomy Centre and Columbia), and N. Mirabal (U. Michigan), report on behalf of the MDM Observatory GRB follow-up team: We monitored the location of Swift GRB 050607 and its decaying X-ray afterglow (Retter et al., GCN #3525; Pagani et al., GCN #3528) in the R band with the MDM 2.4m telescope beginning 16 minutes after the trigger, and extending to 2 hours. Seeing was approximately 1.1". The afterglow candidate discovered by Rhoads (GCN #3527) is present in all of our images with 22.5 < R < 23, and appears to have faded. However, it is difficult for us to characterize its variability at this stage in the analysis as there may also be extended emission. If correct, this is the faintest optical afterglow detected at the equivalent time (Berger et al., astro-ph/0502468), even taking into account the 0.4 magnitudes of R-band Galactic absorption in this direction. Images are posted at http://www.astro.columbia.edu/~jules/grb/050607/