{
  "bibcode": "2009GCN..9963....1P",
  "body": "C. Pagani (PSU), A. P. Beardmore (U Leicester), S. Campana (INAF-OAB),\nV. D'Elia (ASDC), C. Gronwall (PSU), D. Grupe (PSU),\nC. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC),\nN. P. M. Kuin (MSSL), J. Mao (INAF-OAB), P. T. O'Brien (U Leicester),\nJ. P. Osborne (U Leicester), K. L. Page (U Leicester),\nD. M. Palmer (LANL), P. Romano (INAF-IASFPA),\nB. Sbarufatti (INAF-IASFPA), T. N. Ukwatta (GSFC/GWU) and\nL. Vetere (PSU) report on behalf of the Swift Team:\n\nAt 10:09:07 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 090929B (trigger=371050).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 117.705, -0.632 which is \n   RA(J2000) = 07h 50m 49s\n   Dec(J2000) = -00d 37' 55\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a complex structure\nwith most activity in multiple peaks from T-10 sec to T+50 s, and additional\npeaks at T+150 sec, during the XRT observations.  The peak count rate\nwas ~7000 counts/sec (15-350 keV), at ~40 sec after the trigger. \n\nThe XRT began observing the field at 10:10:31.3 UT, 84.1 seconds after\nthe BAT trigger. XRT found a bright, uncatalogued X-ray source located\nat RA, Dec 117.7202, -0.6574 which is equivalent to:\n   RA(J2000)  = 07h 50m 52.84s\n   Dec(J2000) = -00d 39' 26.6\"\nwith an uncertainty of 5.3 arcseconds (radius, 90% containment). This\nlocation is 106 arcseconds from the BAT onboard position, within the\nBAT error circle. No event data are yet available to determine the\ncolumn density using X-ray spectroscopy. \n\nThe initial flux in the 2.5 s image was 1.49e-09 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of  97 seconds with the White\nfilter  starting 93 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 typical\n3-sigma upper limit has been about 19.6 mag.  The 8'x8' region for\nthe list of sources generated on-board covers 100% of the  XRT error\ncircle. The list of sources is typically complete to about 18 mag. No\ncorrection has been made for the expected extinction corresponding to\nE(B-V) of  0.07.  We note there is a bright (10th mag) star less than\n2 arcsec from the XRT position which complicates the analysis of the\nUVOT data. \n\nBurst Advocate for this burst is C. Pagani (pagani AT astro.psu.edu). \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": 9963,
  "createdOn": 1254220632000,
  "email": "palmer@lanl.gov",
  "subject": "GRB 090929B: Swift detection of a burst",
  "submitter": "David Palmer at LANL  <palmer@lanl.gov>",
  "eventId": "GRB 090929B"
}