{
  "bibcode": "2015GCN.17485....1B",
  "body": "D. N. Burrows (PSU), P. D'Avanzo (INAF-OAB), N. Gehrels (NASA/GSFC),\nJ. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),\nF. E. Marshall (NASA/GSFC), T. Sakamoto (AGU) and\nB. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team:\n\nAt 12:16:26 UT and 12:31:11, the Swift Burst Alert Telescope (BAT) triggered\ntwice on an outburst from SGR 1935+2154 (triggers=632158, 632159).  \nSwift slewed immediately to the location. The BAT on-board calculated location \nis RA, Dec 293.724, +21.888 which is \n   RA(J2000) = 19h 34m 54s\n   Dec(J2000) = +21d 53' 16\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve for the first trigger\nshows a single-peaked structure with a duration of about 0.2 sec.  \nThe peak count rate was ~3200 counts/sec (15-350 keV), at ~0 sec \nafter the trigger.  The second light curve also shows a single-peaked \nstructure with a duration of about 0.2 sec.  The peak count rate was \n~11,000 counts/sec (15350 keV), at ~0 sec after the second trigger. \n\nThe XRT began observing the field at 12:17:48.1 UT, 82.0 seconds after\nthe BAT trigger. Using promptly downlinked data we find an X-ray source \nwith an enhanced position: RA, Dec 293.7312, 21.8973 which\nis equivalent to:\n   RA(J2000)  = 19h 34m 55.50s\n   Dec(J2000) = +21d 53' 50.3\"\nwith an uncertainty of 2.5 arcseconds (radius, 90% containment). This\nlocation is 41 arcseconds from the BAT onboard position, within the BAT\nerror circle. This position is consistent with the XRT position reported \nfor this source in Cummings et al. (ATel #6294). This position may be \nimproved as more data are received; the latest position is available \nat http://www.swift.ac.uk/sper. We cannot determine whether the source is \nfading at the present time. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density consistent with the Galactic value of 1.27\nx 10^22 cm^-2 (Willingale et al. 2013). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 86 seconds after the BAT trigger. No credible afterglow candidate has\nbeen found in the initial data products. The 2.7'x2.7' sub-image covers 100% of\nthe XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. \nThe 8'x8' region for the list of sources generated on-board covers 100% of the\nXRT error circle. The list of sources is typically complete to about 18 mag. No\ncorrection has been made for the large, but uncertain extinction expected. \n\nThis source was discovered by Swift in July 5, 2014 (Cummings et al, ATel #6294). \nThis is the first activity since that time.",
  "circularId": 17485,
  "createdOn": 1424609145000,
  "email": "burrows@astro.psu.edu",
  "subject": "Swift detection of an outburst from SGR 1935+2154",
  "submitter": "David Burrows at PSU/Swift  <burrows@astro.psu.edu>",
  "eventId": "SGR 1935+2154"
}