{
  "bibcode": "2012GCN.12980....1S",
  "body": "C. J. Saxton (UCL-MSSL), J. R. Cummings (NASA/UMBC),\nN. P. M. Kuin (UCL-MSSL), A. Y. Lien (NASA/GSFC/ORAU),\nO. M. Littlejohns (U Leicester), C. B. Markwardt (NASA/GSFC),\nF. E. Marshall (NASA/GSFC), C. J. Mountford (U Leicester),\nS. R. Oates (UCL-MSSL), K. L. Page (U Leicester), D. M. Palmer (LANL),\nB. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU), C. A. Swenson (PSU)\nand T. N. Ukwatta (MSU) report on behalf of the Swift Team:\n\nAt 04:39:56 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 120224A (trigger=515976).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 40.975, -17.793 which is \n   RA(J2000) = 02h 43m 54s\n   Dec(J2000) = -17d 47' 32\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a single-peaked\nstructure with a duration of about 10 sec.  The peak count rate\nwas ~1200 counts/sec (15-350 keV), at ~2 sec after the trigger. \n\nThe XRT began observing the field at 04:41:45.6 UT, 109.1 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source located at RA, Dec 40.94380, -17.75959 which is equivalent\nto:\n   RA(J2000)  = 02h 43m 46.51s\n   Dec(J2000) = -17d 45' 34.5\"\nwith an uncertainty of 3.9 arcseconds (radius, 90% containment). This\nlocation is 160 arcseconds from the BAT onboard position, within the\nBAT error circle. This position may be improved as more data are\nreceived; the latest position is available at\nhttp://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 in excess of the Galactic value (2.45 x\n10^20 cm^-2, Kalberla et al. 2005), with an excess column of 3.6\n(+4.34/-3.51) x 10^21 cm^-2 (90% confidence). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 114 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 none of\nthe XRT error circle. The 8'x8' region for the list of sources generated\non-board covers 100% of the XRT error circle. The list of sources is typically\ncomplete to about 18 mag. No correction has been made for the expected\nextinction corresponding to E(B-V) of 0.04. \n\nBurst Advocate for this burst is C. J. Saxton (cjs2 AT mssl.ucl.ac.uk). \nPlease contact the BA by email if you require additional information\nregarding Swift followup of this burst. In extremely urgent cases, after\ntrying the Burst Advocate, you can contact the Swift PI by phone (see\nSwift TOO web site for information: http://www.swift.psu.edu/too.html.)",
  "circularId": 12980,
  "createdOn": 1330059070000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 120224A: Swift detection of a burst",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 120224A"
}