Description
We report on observations of a gamma-ray burst (GRB 061126) with an extremely bright (R~12mag at peak) early-time optical afterglow. The optical afterglow is already fading as a power law 22s after the trigger, with no detectable prompt contribution in our first exposure, which was coincident with a large prompt-emission gamma-ray pulse. The optical-infrared photometric SED is an excellent fit to a power law, but it exhibits a moderate red-to-blue evolution in the spectral index at about 500s after the burst. This color change is contemporaneous with a switch from a relatively fast decay to slower decay.
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