GRB 061121: Broadband spectral evolution through the prompt and afterglow phases of a bright burst

Understand

Swift triggered on a precursor to the main burst of GRB 061121 (z=1.314), allowing observations to be made from the optical to gamma-ray bands.

• Many other telescopes, including Konus-Wind, XMM-Newton, ROTSE and the Faulkes Telescope North, also observed the burst.
• The gamma-ray, X-ray and UV/optical emission all showed a peak ~75s after the trigger, although the optical and X-ray afterglow components also appear early on - before, or during, the main peak.
• Spectral evolution was seen throughout the burst, with the prompt emission showing a clear positive correlation between brightness and hardness.