{
  "bibcode": "2011GCN.12373....1B",
  "body": "W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),\nD. N. Burrows (PSU), S. Campana (INAF-OAB),\nJ. R. Cummings (NASA/UMBC), V. D'Elia (ASDC),\nP. A. Evans (U Leicester), C. Guidorzi (U Ferrara),\nS. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU),\nJ. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),\nO. M. Littlejohns (U Leicester), V. Mangano (INAF-IASFPA),\nF. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),\nP. T. O'Brien (U Leicester), C. Pagani (U Leicester),\nK. L. Page (U Leicester), J. L. Racusin (NASA/GSFC),\nT. Sakamoto (NASA/UMBC), B. Sbarufatti (INAF-OAB/IASFPA),\nM. H. Siegel (PSU), E. Sonbas (GSFC/USRA/Adiyaman Univ.),\nR. L. C. Starling (U Leicester) and B.-B. Zhang (PSU) report on behalf\nof the Swift Team:\n\nAt 13:51:20 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 110921A (trigger=503652).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 294.078, +36.377 which is \n   RA(J2000) = 19h 36m 19s\n   Dec(J2000) = +36d 22' 36\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a ragged, single-peaked\nstructure with a duration of about 10 sec.  The peak count rate\nwas ~1000 counts/sec (15-350 keV), at ~4 sec after the trigger. \n\nThe XRT began observing the field at 13:53:22.5 UT, 122.4 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source located at RA, Dec 294.09838, 36.32882 which is equivalent\nto:\n   RA(J2000)  = 19h 36m 23.61s\n   Dec(J2000) = +36d 19' 43.8\"\nwith an uncertainty of 3.8 arcseconds (radius, 90% containment). This\nlocation is 182 arcseconds from the BAT onboard position, outside 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. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density in excess of the Galactic value (1.43 x\n10^21 cm^-2, Kalberla et al. 2005), with an excess column of 3.1\n(+2.28/-1.97) x 10^21 cm^-2 (90% confidence). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 125 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 0.14. \n\nBurst Advocate for this burst is W. H. Baumgartner (wayne AT milkyway.gsfc.nasa.gov). \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": 12373,
  "createdOn": 1316613714000,
  "email": "burrows@astro.psu.edu",
  "subject": "GRB 110921A: Swift detection of a burst",
  "submitter": "David Burrows at PSU/Swift  <burrows@astro.psu.edu>",
  "eventId": "GRB 110921A"
}