{
  "bibcode": "2023GCN.33598....1P",
  "body": "D. M. Palmer (LANL), S. D. Barthelmy (GSFC),\nA. P. Beardmore (U Leicester), H. A. Krimm (NSF),\nS. Laha (GSFC/UMBC), A. Y. Lien (U Tampa),\nC. B. Markwardt (GSFC), T. Parsotan (GSFC/UMBC),\nT. Sakamoto (AGU), M. Stamatikos (OSU)\n(i.e. the Swift-BAT team):\n\nUsing the data set from T-240 to T+962 sec from the recent telemetry\ndownlink, we report further analysis of BAT GRB 230409B (trigger #1163401)\n(Beardmore et al., GCN Circ. 33592).  The BAT ground-calculated position\nis RA, Dec = 329.516, 52.832 deg which is\n   RA(J2000)  =  21h 58m 03.8s\n   Dec(J2000) = +52d 49' 55.1\"\nwith an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).\nThe partial coding was 32%.\n\nThe mask-weighted light curve shows a single-pulse structure\nthat starts at ~T-1 s, peaks at ~T+1 s, and ends at ~T+12 s.\nThe hump at ~50 s to 100 s mentioned in the previous circular\n(Beardmore et al., GCN Circ. 33592) is due to background fluctuation\nand is not part of the burst. T90 (15-350 keV) is 9.79 +- 2.59 sec\n(estimated error including systematics).\n\nThe time-averaged spectrum from T-0.58 to T+11.78 sec is best fit by a\nsimple\npower-law model.  The power law index of the time-averaged spectrum is\n1.86 +- 0.19.  The fluence in the 15-150 keV band is 9.9 +- 1.2 x 10^-7\nerg/cm2.\nThe 1-sec peak photon flux measured from T+0.43 sec in the 15-150 keV band\nis 3.7 +- 0.5 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/1163401/BA/",
  "circularId": 33598,
  "createdOn": 1681062601000,
  "email": "amy.y.lien@nasa.gov",
  "subject": "GRB 230409B: Swift-BAT refined analysis",
  "submitter": "Amy Lien at GSFC  <amy.y.lien@nasa.gov>",
  "eventId": "GRB 230409B"
}