GCN Circular 3363
N. Mirabal (U. Michigan), M. Boettcher, J. Shields, M. Joshi (Ohio U.), and J. P. Halpern (Columbia U.) report on behalf of the MDM GRB follow-up team: "We monitored the optical afterglow (Yost et al., GCN #3322) of GRB 050502a with the MDM 1.3m telescope beginning on 2005 May 2.163 UT and spanning from 1.8 hr to 8.2 hr after the burst. Preliminary photometry referenced to a USNO-B1.0 star at (J2000) R.A. 13:29:59.84, Decl. +42:43:00.2 listed as R = 16.01, indicates that the OT faded from approximately R~19.3 on May 2.163 to R~21.4 on May 2.36, and continued to decline until the end of the monitoring period. The corresponding power-law decay index is -1.44 +/- 0.2. This is steeper than the decay index of -1.03 estimated from the earlier observations of Yost et al. (GCN #3322)."