{
  "bibcode": "2009GCN..9718....1E",
  "body": "P. A. Evans (U Leicester), S. D. Barthelmy (GSFC),\nW. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),\nM. M. Chester (PSU), S. T. Holland (CRESST/USRA/GSFC),\nN. P. M. Kuin (MSSL), C. B. Markwardt (CRESST/GSFC/UMD),\nK. L. Page (U Leicester), A. Rowlinson (U Leicester),\nM. H. Siegel (PSU), M. A. Stark (PSU) and T. N. Ukwatta (GSFC/GWU)\nreport on behalf of the Swift Team:\n\nAt 22:42:18 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 090727 (trigger=358520).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 315.972, +64.916 which is \n   RA(J2000) = 21h 03m 53s\n   Dec(J2000) = +64d 54' 58\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve shows a single peak\nwith a duration of about 25 sec.  The peak count rate\nwas ~1000 counts/sec (15-350 keV), at ~1 sec after the trigger. \n\nThe XRT began observing the field at 22:43:46.0 UT, 87.9 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source located at RA, Dec 315.96139, 64.92438 which is equivalent\nto:\n   RA(J2000)  = 21h 03m 50.73s\n   Dec(J2000) = +64d 55' 27.8\"\nwith an uncertainty of 4.0 arcseconds (radius, 90% containment). This\nlocation is 34 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 consistent with the Galactic value of\n2.48e+21 cm^-2 (Kalberla et al. 2005). \n\n\nUVOT took a finding chart exposure of nominal 150 seconds with the White filter\nstarting 91 seconds after the BAT trigger. No credible afterglow candidate has\nbeen found in the initial data products. Data from the 2.7'x2.7' sub-image are\nnot available at this time. 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 0.54. \n\n\n\n\nBurst Advocate for this burst is P. A. Evans (pae9 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": 9718,
  "createdOn": 1248735562000,
  "email": "scott@lheamail.gsfc.nasa.gov",
  "subject": "GRB 090727: Swift detection of a burst",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>",
  "eventId": "GRB 090727"
}