{
  "bibcode": "2009GCN..8795....1S",
  "body": "T. Sakamoto (NASA/UMBC), M. M. Chester (PSU), E. A. Hoversten (PSU),\nH. A. Krimm (CRESST/GSFC/USRA), J. Mao (INAF-OAB),\nR. Margutti (Univ Bicocca&OAB), F. E. Marshall (NASA/GSFC),\nD. M. Palmer (LANL), M. Stamatikos (NASA/ORAU),\nT. N. Ukwatta (GSFC/GWU) and L. Vetere (PSU) report on behalf of the\nSwift Team:\n\nAt 23:58:21 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 090111 (trigger=339696).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 251.645, +0.091 which is \n   RA(J2000) = 16h 46m 35s\n   Dec(J2000) = +00d 05' 28\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a double-peaked\nstructure with a duration of about 30 sec.  The peak count rate\nwas ~1200 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 23:59:38.3 UT, 76.6 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nvariable, uncatalogued X-ray source with an enhanced position: RA, Dec\n251.6759, 0.0769 which is equivalent to:\n   RA(J2000)  = 16h 46m 42.21s\n   Dec(J2000) = +00d 04' 36.8\"\nwith an uncertainty of 3.0 arcseconds (radius, 90% containment). This\nlocation is 122 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. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density consistent with the Galactic value of\n6.45e+20 cm^-2 (Kalberla et al. 2005). \n\nThe initial flux in the 2.5 s image was 3.05e-09 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 150 seconds with the White\nfilter  starting 86 seconds after the BAT trigger. No credible\nafterglow candidate has  been found in the initial data products. The\n2.7'x2.7' sub-image covers 100% of  the XRT error circle. The 3-sigma\nupper limit at the location of the XRT candidate is 19.3 mag.  The\n8'x8' region for the list of sources generated on-board covers 100%\nof the  XRT error circle. The list of sources is typically complete\nto about 18 mag. No  correction has been made for the expected\nextinction corresponding to E(B-V) of  0.16. \n\nBurst Advocate for this burst is T. Sakamoto (Taka.Sakamoto AT 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": 8795,
  "createdOn": 1231719321000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 090111: Swift detection of a burst",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 090111"
}