GCN Circular 5771
N. Mirabal (Columbia U.), R. J. Assef & K. Schlesinger (OSU) report on behalf of the MDM Observatory GRB follow-up team: "We observed the Swift error circle of GRB 061028 (Sakamoto et al., GCN 5762) in r', i', and z' bands using the RETROCAM imager on the MDM 2.4m telescope starting on October 28 06:47 UT, 5.35 hours after the trigger. A summed 45-minute exposure in i' reveals no new object in the refined XRT error circle (Cusumano et al., GCN 5767) down to I ~ 21.5 relative to the USNO-B1.0 catalog. We clearly detect sources S1 (Bloom et al., GCN 5768) and S2 (Cenko et al., GCN 5770) at a preliminary magnitude of I ~ 21.0 for both objects, consistent with the measurements reported by Cenko et al (GCN 5770). Results of additional bands will be reported subsequently. This message may be cited."