GCN Circular 1437

V. M. Kaspi (McGill/MIT), F. P. Gavriil (McGill) and P. M.
Woods (USRA/NSSTC), following the discovery of brief X-ray bursts
from the direction of the anomalous X-ray pulsar 1E 2259+586 (IAUC
7924, GCN 1432
Not found
 
 
) on June 18, 2002, report now on further analysis of the same
RXTE/PCA data.  We find that the pulsed flux declined monotonically by
a factor of 4 over the 15 ks in which the bursts were detected, in
concert with the decreasing burst rate over the same interval.  In
addition, the pulse profile during the 15 ks was significantly
different than the long-term average profile, an effect not seen in 5.8
yr of prior RXTE monitoring.  Specifically, the relative amplitudes of
the two peaks in the profile were reversed, and the bridge of emission
usually present between them decreased in amplitude.  These two
observations independently demonstrate that 1E 2259+586 is the origin
of the bursts.  This solidifies the common nature of anomalous X-ray pulsars
and soft gamma repeaters.  Bursting in anomalous X-ray pulsars was
predicted in the magnetar model by Thompson & Duncan (1996; ApJ, 473,
322).  We provide figures including lightcurves, the pulsed flux evolution, 
and pulse profiles both during the burst epoch and the long-term burst
free average, at the following URL: 

http://www.physics.mcgill.ca/~vkaspi/1E2259+586/bursts.html