The bright optical afterglow of the long GRB 001007

We present optical follow up observations of the long GRB 001007 between 6.14 hours and ~468 days after the event. An unusually bright optical afterglow (OA) was seen to decline following a steep power law decay with index $\alpha$ = -2.03 $\pm$ 0.11, possibly indicating a break in the light curve at $t - t_{\rm0} <$ 3.5 days, as found in other bursts. Upper limits imposed by the LOTIS alerting system 6.14 hours after the gamma ray event provide tentative (1.2 $\sigma$) evidence for a break in the optical light curve. The spectral index $\beta$ of the OA yields -1.24 $\pm$ 0.57. These values may be explained both by several fireball jet models and by the cannonball model. Fireball spherical expansion models are not favoured. Late epoch deep imaging revealed the presence of a complex host galaxy system, composed of at least two objects located 1.2´´ (1.7 $\sigma$) and 1.9´´ (2.7 $\sigma$) from the afterglow position.

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