{
  "bibcode": "2009GCN..8939....1G",
  "body": "O. Godet (U Leicester), S. D. Barthelmy (GSFC),\nW. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),\nS. Campana (INAF-OAB), P. A. Evans (U Leicester), J. A. Kennea (PSU),\nR. Margutti (Univ Bicocca&OAB), J. P. Osborne (U Leicester),\nC. Pagani (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL),\nM. Perri (ASDC), P. Romano (INAF-IASFPA),\nB. A. Rowlinson (U Leicester), G. Stratta (ASDC), M. C. Stroh (PSU),\nG. Tagliaferri (INAF-OAB) and L. Vetere (PSU) report on behalf of the\nSwift Team:\n\nAt 13:54:24 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 090306 (trigger=345396).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 16.740, -50.065 which is \n   RA(J2000) = 01h 06m 58s\n   Dec(J2000) = -50d 03' 54\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a short, \nhard structure with a duration less than a single 64 msec timebin. \nThe peak count rate was ~2000 counts/sec (15-350 keV), at ~0 sec\nafter the trigger. \n\nThe XRT began observing the field at 13:55:57.4 UT, 95.5 seconds\nafter the BAT trigger. Using promptly downlinked data we find an\nuncatalogued X-ray source located at RA, Dec 16.74294, -50.00206 which\nis equivalent to:\n   RA(J2000)  = 01h 06m 58.31s\n   Dec(J2000) = -50d 00' 07.4\"\nwith an uncertainty of 4.9 arcseconds (radius, 90% containment). This\nposition may be improved as more data are received; the latest position\nis 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\n1.37e+20 cm^-2 (Kalberla et al. 2005). \n\nAt this time we do not have UVOT data. \n\nThis trigger was the first of a new triggering function\nwithin BAT (the so called Subthreshold trigger).  While there\nis a real source in the XRT initial image, this would say\nthe trigger is a real GRB.  However because we did not receive\nthe usual BAT Position message (for reasons yet unknown),\nwe caution that we can not say with confidence that this is a\nreal burst.  We will not have the full data downlinked\nuntil ~17:00 UT. \n\nBurst Advocate for this burst is O. Godet (og19 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": 8939,
  "createdOn": 1236352860000,
  "email": "scott@lheamail.gsfc.nasa.gov",
  "subject": "GRB 090306: Swift detection of a possible burst",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>",
  "eventId": "GRB 090306"
}