{
  "bibcode": "2020GCN.27665....1S",
  "body": "A Forest of Bursts from SGR 1935+2154\n\n\nDavid M. Palmer (LANL) reports on behalf of the BAT Team:\n\n\n\nAt 18:26:20 of 2020-04-27 UT, the Swift Burst Alert Telescope (BAT)\n\ntriggered and located a burst from the Soft Gamma Repeater SGR 1935+2154\n\n(Trigger #968211) (GCN #27657; Barthelmy et al.). This burst, and many\n\nsubsequent bursts described below, continuing to at least T+7 hours (the\n\ntime of this writing) were also seen by Fermi/GBM (GCN #27659; Fletcher\n\net al.)\n\n\n\nThis initial burst was followed by an intense sequence of bursts\n\nstarting at ~T+300s after the first trigger time. This includes two\n\nseparate time segments, 3 seconds and 15 seconds long, made up of rapid\n\nsequences of multiple bursts during which the count rate never returns\n\nto baseline on the 64 ms timescale (the highest time-resolution data\n\nthat has been downlinked so far).\n\n\n\nDuring those time intervals, the peak count rate reaches up to 130k\n\ncounts/s on a 64 ms timescale over the 15-350 keV band, and 350k\n\ncounts/s on a 1 second timescale over the full detector sensitivity\n\nrange. (The majority of these additional counts would be below the 15 keV \n\ncalibrated energy bin but above the Low-Level-Discriminator level.\n\nThis LLD level varies from detector-to-detector in BAT's 32k-element\n\narray, but is typically 12-14 keV. This indicates that the emission\n\nspectrum is very steep around those energies.)\n\n\n\nDuring the first 24 minutes of the episode, there were at least 35\n\nclearly-distinguishable bursts outside of the piled-up time intervals.\n\n\n\nThis is similar to the forests of bursts seen 2006-03-29 from \n\nSGR 1900+14 (Israel et al, 2008, ApJ 685:1114) and 2008-05-28 from\n\nSGR 1627-41. (GCN #7777; Palmer et al.).\n\n\n\nSGR 1935+2154's recent activation was first detected with a burst 5 days\n\nearlier, which was seen by multiple spacecraft, providing timing\n\ninformation that identified the location to be this source (GCN #27625;\n\nHurley et al.). The previous BAT detection was 9 bursts in ~24 hours in\n\nNovember 2019.\n\n\n\n\n\nNote: A draft copy of this report was accidentally distributed to the \n\nGCN (as #27660) before the final version was submitted to ATel, \n\nand then as this courtesy copy to GCN.  The ATel #13675 submission\n\nis the citable publication of record.",
  "circularId": 27665,
  "createdOn": 1588084126000,
  "email": "dmopalmer@gmail.com",
  "subject": "A Forest of Bursts from SGR 1935+2154",
  "submitter": "David Palmer at LANL  <dmopalmer@gmail.com>",
  "eventId": "SGR 1935+2154"
}