{
  "bibcode": "2018GCN.23123....1S",
  "body": "M. Stamatikos (OSU), S. D. Barthelmy (GSFC),\nJ. R. Cummings (CPI), H. A. Krimm (NSF/USRA),\nA. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),\nM. J. Moss (GWU), D. M. Palmer (LANL),\nT. Sakamoto (AGU), T. N. Ukwatta (LANL)\n(i.e. the Swift-BAT team):\n\nUsing the data set from T-240 to T+963 sec from the recent telemetry downlink,\nwe report further analysis of BAT GRB 180809B (trigger #852553)\n(Moss et al., GCN Circ. 23105).  The BAT ground-calculated position is\nRA, Dec = 299.712, -15.293 deg which is\n  RA(J2000)  =  19h 58m 50.8s\n  Dec(J2000) = -15d 17' 34.0\"\nwith an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).\nThe partial coding was 63%.\n\nThe mask-weighted light curve shows a multi-peaked structure that starts\nat ~T-36 s and ends at ~T+80 s, followed by another pulse that starts\nat ~T+200 s and ends at ~T+250 s. The total burst emission ends at ~T+300 s.\nT90 (15-350 keV) is 233.2 +- 1.1 sec (estimated error including systematics).\n\nWe note that the later pulse overlaps with the XRT flare and some ground-based\noptical observations (e.g. Tiurina et al.; GCN #23113), which indicates an increase\n in the optical magnitude from Mag 16.5 to 15.5 at the pulse time.\n\nThe time-averaged spectrum from T-36.1 to T+302.3 sec is best fit by a simple\npower-law model.  The power law index of the time-averaged spectrum is\n1.26 +- 0.02.  The fluence in the 15-150 keV band is 7.3 +- 0.1 x 10^-5 erg/cm2.\nThe 1-sec peak photon flux measured from T+35.10 sec in the 15-150 keV band\nis 26.3 +- 0.6 ph/cm2/sec.  All the quoted errors are at the 90% confidence\nlevel.\n\nThe results of the batgrbproduct analysis are available at\nhttp://gcn.gsfc.nasa.gov/notices_s/852553/BA/",
  "circularId": 23123,
  "createdOn": 1533925237000,
  "email": "amy.y.lien@nasa.gov",
  "subject": "GRB 180809B, Swift-BAT refined analysis",
  "submitter": "Amy Lien at GSFC  <amy.y.lien@nasa.gov>",
  "eventId": "GRB 180809B"
}