{
  "bibcode": "2012GCN.13913....1S",
  "body": "R. L. C. Starling (U Leicester), C. Gronwall (PSU),\nH. A. Krimm (CRESST/GSFC/USRA), K. L. Page (U Leicester),\nD. M. Palmer (LANL), M. H. Siegel (PSU) and T. N. Ukwatta (MSU) report\non behalf of the Swift Team:\n\nAt 05:04:31 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 121028A (trigger=536897).  Swift slewed immediately to the burst.   \nThe BAT on-board calculated location is\nRA, Dec 271.923, -2.285 which is\n  RA(J2000) = 18h 07m 42s\n  Dec(J2000) = -02d 17' 04\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including\nsystematic uncertainty).  The BAT light curve showed a multi-peaked\nstructure with a duration of about 30 sec.  The peak count rate\nwas ~2500 counts/sec (15-350 keV), at ~1 sec after the trigger.\n\nThe XRT began observing the field at 05:06:41.7 UT, 129.8 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source with an enhanced position: RA, Dec 271.8995, -2.2936 which\nis equivalent to:\n   RA(J2000)  = 18h 07m 35.89s\n   Dec(J2000) = -02d 17' 36.8\"\nwith an uncertainty of 2.3 arcseconds (radius, 90% containment). This\nlocation is 90 arcseconds from the BAT onboard position, within the BAT  \nerror circle. This position may be improved as more data are received;   \nthe latest position is 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 in excess of the Galactic value (2.48 x\n10^21 cm^-2, Kalberla et al. 2005), with an excess column of 4.4\n(+4.35/-3.23) x 10^21 cm^-2 (90% confidence).\n\nUVOT took a finding chart exposure of 150  seconds with the White filter starting\n134 seconds after the BAT trigger. No credible afterglow candidate has been\nfound in the initial data products. The 2.7'x2.7' sub-image covers 100% of the\nXRT error circle. The typical 3-sigma upper limit has been about 19.2 mag. The\n8'x8' region for the list of sources generated on-board covers 100% of the XRT\nerror circle. The list of sources is typically complete to about 18.0 mag. No\ncorrection has been made for extinction.\n\nDue to the maintenance work at Goddard this weekend (GCN 13905) there\nmay be a delay in receiving the full dataset, and thus refined\nanalyses may not be available until late Sunday/early Monday.\n\nBurst Advocate for this burst is R. L. C. Starling (rlcs1 AT star.le.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": 13913,
  "createdOn": 1351402263000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 121028A: Swift detection of a burst",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 121028A"
}