GCN Circular 13188
B. E. Cobb (GWU), reports: Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 120327A (GCN 13123, Sbarufatti et al.) over several epochs, starting ~1.8 hours post-burst. For each epoch, several dithered images were obtained with total summed exposure times of 15 min in V and I and 12 min in J and K. The fading afterglow of GRB 120327A (e.g. GCN 13123, Sbarufatti et al.; GCN 13124, Klotz et al.; GCN 13125, Smith et al.) was detected with the following magnitudes (or 3-sigma limits): mid-exposure time V mag I mag J mag K mag 1.8 hrs 18.92+/-0.03 17.73+/-0.04 16.46+/-0.07 14.83+/-0.09 4.1 hrs 19.97+/-0.03 18.57+/-0.04 17.42+/-0.08 15.73+/-0.09 25.8 hrs >21.9 >20.9 >19.0 >17.4 (Optical photometry is calibrated against Landolt standard stars and IR photometry is calibrated against 2MASS stars in the field.) Between about 1.8 hrs and 4.1 hrs post-burst, the GRB afterglow fades with a decay rate of approximately alpha = 1 (where afterglow flux is proportional to t^-alpha).