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Continued Activity of SGR 0501+4516

ATEL # 1678; David Palmer (LANL) on behalf of the Swift Team
on 24 Aug 2008; 5:13 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: David M. Palmer (

Subjects: X-ray, Gamma Ray, Soft Gamma-ray Repeaters
Referred to by ATEL #: 1683

SGR 0501+4516 (ATEL #1676, Barthelmy et al.; and other recent ATELs and GCNs) continues to be active, with 32 bursts detected and identified by Swift-BAT in the 36 hours following the first detected burst at 2008-08-22 12:41:59 UT. (A comparable number of bursts presumably occurred during the intervals when the SGR was behind the Earth as seen from Swift.)

For most of these bursts, Swift was directly observing the source with XRT and UVOT. The SGR is Moon-constrained for XRT and UVOT currently (from ~2008-08-24 02:00 to ~2008-08-26 05:00 UT), however Swift will be pointed to keep the SGR in the BAT field-of-view when possible.

A list of burst times follows. Times are from the BAT onboard trigger, which usually corresponds to an instant somewhere between the onset and the peak of the event, and are not barycentered. Trigger duration is a reasonable proxy for burst duration in most cases. Except for the bursts detected during slews, all have been verified by BAT imaging to have come from the SGR. The brighter bursts, with BAT instrumental fluences above 2000 counts, are marked with asterisks. The very brightest bursts have fluxes in the kiloCrab range.

SGR 0501+4516 burst times
BAT Trigger time UT Trig dur (ms) Notes
2008-08-22T12:41:59.457 64 *
2008-08-22T13:09:04.353 256
2008-08-22T13:12:52.697 16 *
2008-08-22T13:20:30 slew
2008-08-22T14:17:55.361 256
2008-08-22T14:34:26.493 32
2008-08-22T17:29:30.017 64
2008-08-22T22:24:24.008 32
2008-08-22T22:36:53.368 32
2008-08-22T22:53:50.760 16
2008-08-23T00:28:12.536 32
2008-08-23T02:11:39 * slew 13kcounts
2008-08-23T04:47:48.599 16 * 35kcounts
2008-08-23T06:31:36.571 16
2008-08-23T06:58:15 slew
2008-08-23T08:30:04.191 16 *
2008-08-23T08:34:56.719 32
2008-08-23T11:07:37.827 16
2008-08-23T11:27:35.107 16 * 90kcounts
2008-08-23T14:27:37.018 64
2008-08-23T14:56:26.238 64 *
2008-08-23T16:31:22.326 16
2008-08-23T17:35:14.362 32 * 17kcounts
2008-08-23T17:35:14.910 128
2008-08-23T17:59:01.430 8
2008-08-23T19:08:09.886 128
2008-08-23T20:49:10.238 256
2008-08-23T20:53:29.110 16
2008-08-23T21:09:19.518 32
2008-08-23T21:11:17.210 64
2008-08-23T21:11:19.630 16
2008-08-23T21:13:39.838 64
2008-08-23T22:37:55.349 08

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R. E. Rutledge , Editor
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