We report a major outburst from the Anomalous X-ray Pulsar 1E 2259+586 , in which over 80 X-ray bursts were detected in four hours using the Rossi X-ray Timing Explorer .
The bursts range in duration from 2 ms to 3 s and have fluences in the 2–10 keV band that range from 3 \times 10 ^ { -11 } to 5 \times 10 ^ { -9 } erg cm ^ { -2 } .
We simultaneously observed increases of the pulsed and persistent X-ray emission by over an order of magnitude relative to quiescent levels .
Both decayed significantly during the course of our 14 ks observation .
Correlated spectral hardening was also observed , with the spectrum softening during the observation .
In addition , we observed a pulse profile change , in which the amplitudes of the two peaks in the pulse profile were swapped .
The profile relaxed back to its pre-outburst morphology after \sim 6 days .
The pulsar also underwent a sudden spin-up ( \Delta \nu / \nu = 4 \times 10 ^ { -6 } ) , followed by a large ( factor of \sim 2 ) increase in spin-down rate which persisted for > 18 days .
We also observed , using the Gemini -North telescope , an infrared enhancement , in which the K _ { s } ( 2.15 \mu m ) flux increased , relative to that measured in a observation made in 2000 , by a factor of \sim 3 , three days post-outburst .
The IR counterpart then faded by a factor of \sim 2 one week later .
In addition , we report an upper limit of 50 \mu Jy on radio emission at 1.4 GHz two days post-outburst .
The X-ray properties of this outburst are like those seen only in Soft Gamma Repeaters .
This conclusively unifies Anomalous X-ray Pulsars and Soft Gamma Repeaters , as predicted uniquely by the magnetar model .