This paper discusses Swift observations of the \gamma -ray burst GRB 050315 ( z=1.949 ) from 80 s to 10 days after the onset of the burst .
The X-ray light curve displayed a steep early decay ( t ^ { -5 } ) for \sim 200 s and several breaks .
However , both the prompt hard X-ray/ \gamma -ray emission ( observed by the BAT ) and the first \sim 300 s of X-ray emission ( observed by the XRT ) can be explained by exponential decays , with similar decay constants .
Extrapolating the BAT light curve into the XRT band suggests the rapidly decaying , early X-ray emission was simply a continuation of the fading prompt emission ; this strong similarity between the prompt \gamma -ray and early X-ray emission may be related to the simple temporal and spectral character of this X-ray rich GRB .
The prompt ( BAT ) spectrum was a steep down to \sim 15 keV , and appeared to continue through the XRT bandpass , implying a low peak energy , inconsistent with the Amati relation .
Following the initial steep decline the X-ray afterglow did not fade for \sim 1.2 \times 10 ^ { 4 } s , after which time it decayed with a temporal index of \alpha \approx 0.7 , followed by a second break at \sim 2.5 \times 10 ^ { 5 } s to a slope of \alpha \sim 2 .
The apparent ‘ plateau ’ in the X-ray light curve , after the early rapid decay , makes this one of the most extreme examples of the steep-flat-steep X-ray light curves revealed by Swift .
If the second afterglow break is identified with a jet break then the jet opening angle was \theta _ { 0 } \sim 5 ^ { \circ } , and implying E _ { \gamma } \mathrel { \hbox { \hbox to 0.0 pt { \hbox { \lower 4.0 pt \hbox { $ \sim$ } } } \hbox% { $ > $ } } } 10 ^ { 50 } erg .