GCN Circular 8637
D. A. Perley (UC Berkeley) reports on behalf of a larger collaboration: During morning twilight on 2008-12-07 UT (starting at 15:40) we undertook additional imaging of the optical transient associated with GRB 081203B, using GMOS on Gemini-North. We report the following magnitudes: g = 22.67 +/- 0.11 (t = 4.076 day) r = 22.41 +/- 0.10 (t = 4.079 day) i = 22.16 +/- 0.20 (t = 4.082 day) Assuming a burst time of 13:52:02 UT (GCN 8600). The SED is well-fit by a power-law with beta = 1.0 +/- 0.3. The power-law index of the light curve compared with our r-band measurement the previous night (GCN 8631) is alpha = 1.6 +/- 0.3. Both values are consistent with typical late-time GRB afterglow behavior. We thank the Gemini staff for conducting these observations, which were carried out under program GN-2008B-Q-6.