GRB 061007 is the brightest gamma-ray burst ( GRB ) to be detected by Swift and is accompanied by an exceptionally luminous afterglow that had a V -band magnitude < 11.1 at 80 s after the prompt emission .
From the start of the Swift observations the afterglow decayed as a power law with a slope of \alpha _ { X } = 1.66 \pm 0.01 in the X-ray and \alpha _ { opt } = 1.64 \pm 0.01 in the UV/optical , up to the point that it was no longer detected above background in the optical or X-ray bands .
The brightness of this GRB and the similarity in the decay rate of the X-ray , optical and \gamma -ray emission from 100 s after the trigger distinguish this burst from others and present a challenge to the fireball model .
The lack of a cooling or jet break in the afterglow up to \sim 10 ^ { 5 } s constrains any model that can produce the large luminosity observed in GRB 061007 , which we found to require either an excessively large kinetic energy or highly collimated outflow .
Analysis of the multi-wavelength spectral and high-resolution temporal data taken with Swift suggest an early time jet-break to be a more plausible scenario .
This must have occurred within 80 s of the prompt emission , which places an upper limit on the jet opening angle of \theta _ { j } = 0.8 ^ { \circ } .
Such a highly collimated outflow resolves the energy budget problem presented in a spherical emission model , reducing the isotropic equivalent energy of this burst to E _ { \gamma } ^ { corr } = 10 ^ { 50 } ergs ; consistent with other GRBs .