TITLE:   GCN CIRCULAR
NUMBER:  8637
SUBJECT: GRB 081203B: Additional Gemini imaging
DATE:    08/12/08 05:07:27 GMT
FROM:    Daniel Perley at U.C. Berkeley  <dperley@astro.berkeley.edu>

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.