{
  "bibcode": "2012GCN.12914....1B",
  "body": "D. N. Burrows (PSU), M. M. Chester (PSU), V. D'Elia (ASDC),\nD. M. Palmer (LANL), P. Romano (INAF-IASFPA), C. J. Saxton (UCL-MSSL),\nE. Sonbas (NASA/GSFC/Adiyaman Univ.), M. Stamatikos (OSU/NASA/GSFC)\nand G. Stratta (ASDC) report on behalf of the Swift Team:\n\nAt 11:47:24 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated a burst consistent with the known High Mass X-Ray binary\nLS I +61 303 (trigger=513505).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 40.100, +61.220 which is \n   RA(J2000) = 02h 40m 24s\n   Dec(J2000) = +61d 13' 13\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a single short spike\nwith a duration of about 64 ms or less.  The peak count rate\nwas 1500 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 11:48:42.0 UT, 77.5 seconds after\nthe BAT trigger. Using promptly downlinked data we find an X-ray source\nwith an enhanced position: RA, Dec 40.1326, 61.2290 which is equivalent\nto:\n   RA(J2000)  = 02h 40m 31.83s\n   Dec(J2000) = +61d 13' 44.4\"\nwith an uncertainty of 2.1 arcseconds (radius, 90% containment). This\nposition may be improved as more data are received; the latest position\nis available at http://www.swift.ac.uk/sper. This position is 1.2\narcseconds from that of a known X-ray source: LS I +61 303, and\n65.1 arcseconds from the on-board BAT position. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density consistent with the Galactic value of 7.57\nx 10^21 cm^-2 (Kalberla et al. 2005). \n\nUVOT took a finding chart exposure of 150 seconds with the White \nfilter starting 80 seconds after the BAT trigger, and a finding chart \nexposure of 250 seconds with the U filter starting 293 seconds after \nthe BAT trigger.  A source consistent with the position of LS I +61 \n303 is detected, with white = 13.8 and u = 12.5 (1-sigma errors of\nabout 0.1.).  The 2.7'x2.7'  sub-image covers 100% of the XRT error\ncircle.  The 8'x8' region for  the list of sources generated on-board\ncovers 100% of the  XRT error  circle. The list of sources is\ntypically complete to about 18 mag. No   correction has been made for\nthe large, but uncertain extinction  expected. \n\nThe BAT position is within 1.1 arcminutes of the micro-quasar source\nLS I +61 303, and the XRT position is consistent in both position and\nobservational characteristics to our previous observations of this\nsource.  This location has previously been the source of similar\nmagnetar-like bursts (Torres et al. Astrophys. J., 744, 106 (2012)).",
  "circularId": 12914,
  "createdOn": 1328444711000,
  "email": "palmer@lanl.gov",
  "subject": "Swift detection of a burst from LS I +61 303",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>"
}