The robotic ROTSE-III telescope network detected prompt optical emission
contemporaneous with the gamma-ray emission of Swift events GRB051109A and
GRB051111. Both datasets have continuous coverage at high signal-to-noise
levels from the prompt phase onwards, thus the early observations are readily
compared to the Swift XRT and BAT high energy detections. In both cases, the
optical afterglow is established, declining steadily during the prompt
emission. For GRB051111, there is evidence of an excess optical component
during the prompt emission. The component is consistent with the flux
spectrally extrapolated from the gamma-rays, using the gamma-ray spectral
index. A compilation of spectral information from previous prompt detections
shows that such a component is unusual. The existence of two prompt optical
components - one connected to the high-energy emission, the other to separate
afterglow flux, as indicated in GRB051111 - is not compatible with a simple
``external-external'' shock model for the GRB and its afterglow.Comment: ApJ accepted. 32 pages (in preprint form), 5 tables, 5 figure