{
  "bibcode": "2009GCN.10081....1M",
  "body": "C. B. Markwardt (CRESST/GSFC/UMD), S. D. Barthelmy (GSFC),\nA. P. Beardmore (U Leicester), D. N. Burrows (PSU),\nP. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), D. Grupe (PSU),\nC. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC),\nE. A. Hoversten (PSU), J. A. Kennea (PSU), V. Mangano (INAF-IASFPA),\nJ. Mao (INAF-OAB), F. E. Marshall (NASA/GSFC),\nK. L. Page (U Leicester), D. M. Palmer (LANL),\nP. Romano (INAF-IASFPA), P. Roming (PSU), B. Sbarufatti (INAF-IASFPA),\nM. H. Siegel (PSU) and M. Stamatikos (OSU/NASA/GSFC) report on behalf\nof the Swift Team:\n\nAt 13:11:30 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 091026 (trigger=373871).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 276.583, -86.121 which is \n   RA(J2000)  =  18h 26m 20s\n   Dec(J2000) = -86d 07' 16\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows a FRED pulse\nwith a duration of about 20 sec.  The peak count rate\nwas ~2500 counts/sec (15-350 keV), at ~0 sec after the trigger. \n\nThe XRT began observing the field at 13:12:48.9 UT, 78.7 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nuncatalogued X-ray source located at RA, Dec 276.59337, -86.11056 which\nis equivalent to:\n   RA(J2000)  = 18h 26m 22.41s\n   Dec(J2000) = -86d 06' 38.0\"\nwith an uncertainty of 4.0 arcseconds (radius, 90% containment). This\nlocation is 37 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 (8.36e+20\ncm^-2, Kalberla et al. 2005), with an excess column of 3.6\n(+2.72/-2.29) x 10^21 cm^-2 (90% confidence). \n\nThe initial flux in the 2.5 s image was 3.42e-09 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 87 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 C. B. Markwardt (Craig.Markwardt 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": 10081,
  "createdOn": 1256563389000,
  "email": "scott@lheamail.gsfc.nasa.gov",
  "subject": "GRB 091026: Swift detection of a Gamma Ray Burst",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>",
  "eventId": "GRB 091026"
}