{
  "bibcode": "2009GCN..9725....1M",
  "body": "V. Mangano (INAF-IASFPA), S. D. Barthelmy (GSFC),\nA. P. Beardmore (U Leicester), D. N. Burrows (PSU),\nP.A. Curran (MSSL-UCL), P. A. Evans (U Leicester),\nN. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC),\nE. A. Hoversten (PSU), J. A. Kennea (PSU), N. P. M. Kuin (MSSL),\nF. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester),\nP. Romano (INAF-IASFPA), T. Sakamoto (NASA/UMBC),\nB. Sbarufatti (INAF-IASFPA), M. H. Siegel (PSU),\nM. Stamatikos (NASA/ORAU) and M. A. Stark (PSU) report on behalf of\nthe Swift Team:\n\nAt 14:45:45 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 090728 (trigger=358574).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 29.660, +41.647 which is \n   RA(J2000) = 01h 58m 38s\n   Dec(J2000) = +41d 38' 49\"\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 20 sec.  The peak count rate\nwas ~1000 counts/sec (15-350 keV), at ~2 sec after the trigger. \n\nThe XRT began observing the field at 14:47:36.5 UT, 110.6 seconds after\nthe BAT trigger. Using promptly downlinked data we find a bright,\nuncatalogued X-ray source located at RA, Dec 29.65234, 41.63270 which\nis equivalent to:\n   RA(J2000)  = 01h 58m 36.56s\n   Dec(J2000) = +41d 37' 57.7\"\nwith an uncertainty of 4.2 arcseconds (radius, 90% containment). This\nlocation is 55 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\n7.35e+20 cm^-2 (Kalberla et al. 2005). \n\nThe initial flux in the 2.5 s image was 3.90e-10 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 250 seconds with the U filter starting\n116 seconds after the BAT trigger. No credible afterglow candidate has been\nfound in the initial data products. The 2.7'x2.7' sub-image covers 100% of the\nXRT error circle. The 3-sigma upper limit is about 19.2 mag. The\n8'x8' region for the list of sources generated on-board covers 100% of the XRT\nerror circle. The list of sources is typically complete to about 18.0 mag. No\ncorrection has been made for the expected extinction corresponding to E(B-V) of\n0.07. The XRT position is near a bright (< 6.5 mag) star. \n\nBurst Advocate for this burst is V. Mangano (vanessa AT ifc.inaf.it). \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": 9725,
  "createdOn": 1248793204000,
  "email": "scott@lheamail.gsfc.nasa.gov",
  "subject": "GRB 090728: Swift detection of a burst",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>",
  "eventId": "GRB 090728"
}