{
  "bibcode": "2012GCN.13203....1D",
  "body": "V. D'Elia (ASDC), S. D. Barthelmy (GSFC),\nW. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU),\nS. Campana (INAF-OAB), M. M. Chester (PSU), J. A. Kennea (PSU),\nC. B. Markwardt (NASA/GSFC), A. Maselli (INAF-IASFPA),\nA. Melandri (INAF-OAB), P. T. O'Brien (U Leicester),\nT. Sakamoto (NASA/UMBC), C. J. Saxton (UCL-MSSL),\nB. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU), G. Stratta (ASDC),\nC. A. Swenson (PSU), T. N. Ukwatta (MSU) and B.-B. Zhang (PSU) report\non behalf of the Swift Team:\n\nAt 20:33:56 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 120403B (trigger=519256).  Because of an observing constraint,\nthe slew to the burst was delayed by 12.9 minutes. \nThe BAT on-board calculated location is \nRA, Dec 54.809, -89.037, which is \n   RA(J2000)  =  03h 39m 14s\n   Dec(J2000) = -89d 02' 12\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows several spikes\nwith a total duration of about 10 sec.  The peak count rate\nwas ~2000 counts/sec (15-350 keV), at ~1 sec after the trigger. \n\nThe XRT began observing the field at 20:49:04.0 UT, 907.5 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source located at RA, Dec 55.33838, -89.00933 which is equivalent\nto:\n   RA(J2000)  = 03h 41m 21.21s\n   Dec(J2000) = -89d 00' 33.6\"\nwith an uncertainty of 3.9 arcseconds (radius, 90% containment). This\nlocation is 104 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 consistent with the Galactic value of 9.52\nx 10^20 cm^-2 (Kalberla et al. 2005). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 910 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 expected extinction corresponding to E(B-V) of\n0.13. \n\nBurst Advocate for this burst is V. D'Elia (delia AT asdc.asi.it). \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": 13203,
  "createdOn": 1333487029000,
  "email": "scott@milkyway.gsfc.nasa.gov",
  "subject": "GRB 120403B: Swift detection of a burst",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 120403B"
}