{
  "bibcode": "2012GCN.12829....1B",
  "body": "S. D. Barthelmy (GSFC), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC),\nB. Gendre (ASDC), C. Guidorzi (U Ferrara),\nH. A. Krimm (CRESST/GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU),\nO. M. Littlejohns (U Leicester), D. M. Palmer (LANL),\nP. Romano (INAF-IASFPA), B. Sbarufatti (INAF-OAB/PSU),\nR. L. C. Starling (U Leicester), G. Stratta (ASDC) and\nG. Tagliaferri (INAF-OAB) report on behalf of the Swift Team:\n\nAt 13:09:38 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated an outburst from AXP 4U 0142+61 (trigger=511611).  Swift slewed\nimmediately to the burst.  The BAT on-board calculated location is \nRA, Dec 26.621, +61.763 which is \n   RA(J2000)  =  01h 46m 29s\n   Dec(J2000) = +61d 45' 48\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows a single spike\nwith a total duration about 64 millisec.  The peak count rate\nwas ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 13:10:56.9 UT, 78.5 seconds after\nthe BAT trigger. Using promptly downlinked data we find an X-ray source\nlocated at RA, Dec 26.59414, 61.75160 which is equivalent to:\n   RA(J2000)  = 01h 46m 22.59s\n   Dec(J2000) = +61d 45' 05.8\"\nwith an uncertainty of 3.8 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 3.0\narcseconds from that of a known X-ray source: AXP 4U 0142+61. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density consistent with the Galactic value of 8.13\nx 10^21 cm^-2 (Kalberla et al. 2005). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 82 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 coverage of the XRT error circle by the 8'x8' region for the list of\nsources generated on-board is uncertain because the large number of sources\nfilled the available telemetry. The list of sources is typically complete to\nabout 18 mag. No correction has been made for the large, but uncertain\nextinction expected. \n\nThis source has produced previous SGR bursts (most recently last July,\nOates et al. GCN 12209) and is part of a regular monitoring program\nof AXPs (PI: V. Kaspi).",
  "circularId": 12829,
  "createdOn": 1326375031000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "Swift detection of an SGR burst from AXP 4U 0142+61",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>"
}