GCN Circular 13430

A. Lacluyze, J. Haislip, K. Ivarsen, D. Reichart, J. Moore, H. T. 
Cromartie, R. Egger, A. Foster, N. Frank, M. Nysewander, A. Oza, E. 
Speckhard, A.Trotter, and J. A. Crain report:

Skynet observed the field of GRB12711 (INTEGRAL trigger 6599) in B, V, and 
R starting 37 seconds after the burst.  Although no afterglow was detected 
in the initial exposures, a transient source was detected at 06:18:42.839 
-70:59:56.78 (J2000).  The source rapidly brightened, peaking at roughly 
112 seconds after the trigger.  Preliminary peak magnitudes, calibrated to 
~5 UNSO B1.0 stars are as follows:

Time	Tel	Filt	Mag	1sigERR
112	P4	R	12.117	0.008 
113	P1	V	12.593	0.014
116	P3	B	14.061	0.014

The post-peak temporal index is estimated to be -2.1, suggesting a reverse 
shock.

Further observations are ongoing.