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4 Bursts from AXP 4U 0142+61

ATel #845; R. Dib, V. Kaspi (McGill); F. Gavriil (NASA/GSFC); P. Woods (Dynetics)
on 28 Jun 2006; 05:14 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Victoria Kaspi (vkaspi@physics.mcgill.ca)

Subjects: X-ray, Request for Observations, Neutron Star, Soft Gamma-ray Repeater, Transient, Pulsar

On MJD 53911.05 (June 25, 2006) during regular RXTE/PCA monitoring of AXP 4U 0142+61, we detected four SGR-like bursts within 4 min, along with a pulsed flux enhancement. The first burst was detected at 1:20:13 UTC, lasted approximately 0.6 seconds, and had a total fluence of approximately 100 counts in 2-20 keV with 3 operational PCUs. The second burst was detected at 1:20:14 UTC (0.7 seconds after the first burst), lasted approximately 1.5 seconds, and had a total fluence of approximately 200 counts. The third burst was detected at 01:20:28 UTC (14 seconds after the first burst), lasted approximately 1 second and had a total fluence of approximately 100 counts. The fourth burst was detected at 01:24:19 UTC (230 seconds after the first burst), lasted approximately 0.6 seconds and had a total fluence of approximately 100 counts. All times above are barycentric. All four bursts may have been followed by tens-of-seconds-long tails where the pulsed flux is enhanced, but further analysis is required to confirm this. The pulsed flux of the source appears to be significantly enhanced (by about 60% in 2-9 keV) during the observation where the bursts were detected. The source seems to be in an unusal active phase. The only previous burst detection was recently, on April 6, 2006 (ATEL #794). That burst was accompanied by a timing anomaly and a pulse profile change. Additional observations at other wavelengths are strongly encouraged.