{
  "bibcode": "2010GCN.10722....1B",
  "body": "A. P. Beardmore (U Leicester), D. N. Burrows (PSU),\nS. Campana (INAF-OAB), S. T. Holland (CRESST/USRA/GSFC),\nJ. A. Kennea (PSU), W.B Landsman (GSFC), K. L. Page (U Leicester),\nD. M. Palmer (LANL), P. Romano (INAF-IASFPA), M. H. Siegel (PSU),\nM. Stamatikos (OSU/NASA/GSFC), M. A. Stark (PSU) and\nR. L. C. Starling (U Leicester) report on behalf of the Swift Team:\n\nAt 14:37:44 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated a short soft burst (trigger=421262) consistent with the\nlocation of the SNR Kes 73.  Because this source was identified\non board, it did not reach an automatic merit sufficient to cause\na slew.  The BAT on-board calculated location is \nRA, Dec 280.331, -4.921 which is \n   RA(J2000) = 18h 41m 19s\n   Dec(J2000) = -04d 55' 15\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows a single high bin\nat the 64 ms timescale, with an effective count rate of 4000 count/s\n0.1 s after the nominal trigger time.  The count rate during the\n16 ms trigger interval averaged 12000 counts/s. \n\nWhen it was realized that this SNR contains a known magnetar AXP,\nand that this burst is consistent with Soft Gamma Repeater activity,\nwe manually upgraded this target to ensure slewing. \n\nThe XRT began observing the field at 15:09:15.9 UT, 1891.3 seconds\nafter the BAT trigger. Using promptly downlinked data we find an X-ray\nsource located at RA, Dec 280.33059, -4.93731 which is equivalent to:\n   RA(J2000)  = 18h 41m 19.34s\n   Dec(J2000) = -04d 56' 14.3\"\nwith an uncertainty of 4.4 arcseconds (radius, 90% containment), which is \n3.2 arcseconds from the location of 1E 1841-04.5 (AKA PSR J1841-0456). This\nposition may be improved as more data are received; the latest position\nis available at http://www.swift.ac.uk/sper. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density consistent with the Galactic value of\n1.57e+22 cm^-2 (Kalberla et al. 2005). \n\nUVOT took a finding chart exposure of 150 seconds with the White\nfilter  starting 1895 seconds after the BAT trigger. The full 2.7'x2'7\nsub-image has not been received and the partial image does not cover the\nXRT error circle. The 8'x8' region for the list of sources generated\non-board confirms a known optical source within the XRT circle. The\npreliminary UVOT position is RA, Dec 280.33001, -4.93763 which is\n\n   RA(J2000) =  18h 41m 19.20s  \n   Dec(J2000) = -04d 56' 15.5\"\n\nwith an  estimated uncertainty of 1.1 arcsec (radius, 90% confidence,  \nstatistical + systematic).  The white magnitude is 17.98 +- 0.35\nNo correction has been made for the large, but uncertain extinction\nexpected.",
  "circularId": 10722,
  "createdOn": 1273159801000,
  "email": "palmer@lanl.gov",
  "subject": "An SGR-like burst from the magnetar 1E 1841-04.5 in Kes 73",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>"
}