We present a multiwavelength analysis of Swift GRB 061007 .
The 2-m robotic Faulkes Telescope South ( FTS ) began observing 137 s after the onset of the \gamma -ray emission , when the optical counterpart was already decaying from R \sim 10.3 mag , and continued observing for the next 5.5 hours .
These observations begin during the final \gamma -ray flare and continue through and beyond a long , soft tail of \gamma -ray emission whose flux shows an underlying simple power-law decay identical to that seen at optical and X-ray wavelengths , with temporal slope \alpha \sim 1.7 ( F \propto~ { } t ^ { - \alpha } ) .
This remarkably simple decay in all of these bands is rare for Swift bursts , which often show much more complex light curves .
We suggest the afterglow emission begins as early as 30 - 100 s and is contemporaneous with the on-going variable prompt emission from the central engine , but originates from a physically distinct region dominated by the forward shock .
The afterglow continues unabated until at least \sim 10 ^ { 5 } seconds showing no evidence of a break .
The observed multiwavelength evolution of GRB 061007 is explained by an expanding fireball whose optical , X-ray and late-time \gamma -ray emission is dominated by emission from a forward shock with typical synchrotron frequency , \nu _ { m } , that is already below the optical band as early as t=137 s and a cooling frequency , \nu _ { c } , above the X-ray band to at least t=10 ^ { 5 } s. In contrast , the typical frequency of the reverse shock lies in the radio band at early time .
We suggest that the unexpected lack of bright optical flashes from the majority of Swift GRBs may be explained with a low \nu _ { m } originating from small microphysics parameters , \epsilon _ { e } and \epsilon _ { B } .
We derive a minimum jet opening angle \theta = 4.7 ^ { \circ } from the optical light curves and conclude that GRB 061007 is a secure outlier to spectral energy correlations because no X-ray jet break occurred before t \sim 10 ^ { 6 } s .