{
  "submitter": "Rahul Gupta at NASA GSFC <rahul.gupta@nasa.gov>",
  "body": "T. Parsotan (GSFC), S. D. Barthelmy (GSFC), \nR. Gupta (GSFC), H. A. Krimm (NSF),\nS. Laha (GSFC/UMBC), A. Y. Lien (U Tampa),\nC. B. Markwardt (GSFC), M. J. Moss (GSFC),\nD. M. Palmer (LANL), D. Sadaula (GSFC/UMBC),\nT. Sakamoto (AGU), M. H. Siegel (PSU)\n(i.e. the Swift-BAT team):\n \nUsing the data set from T-239 to T+963 sec from the recent telemetry downlink,\nwe report further analysis of BAT GRB 250509A (trigger #1311764)\n(Siegel, et al., GCN Circ. 40407).  The BAT ground-calculated position is\nRA, Dec = 46.451, -38.854 deg which is \n   RA(J2000)  =  03h 05m 48.3s \n   Dec(J2000) = -38d 51' 15.1\" \nwith an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).\nThe partial coding was 96%.\n \nThe mask-weighted BAT light curve shows a sharp rise and exponential decay profile. \nT90 (15-350 keV) is 55.43 +- 10.47 sec (estimated error including systematics).\n \nThe time-averaged spectrum from T-2.85 to T+71.46 sec is best fit by a simple\npower-law model.  The power law index of the time-averaged spectrum is\n1.54 +- 0.08.  The fluence in the 15-150 keV band is 2.4 +- 0.1 x 10^-06 erg/cm2.\nThe 1-sec peak photon flux measured from T+0.42 sec in the 15-150 keV band\nis 1.9 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence\nlevel. \n \nThe results of the batgrbproduct analysis are available at\nhttps://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1311764\n",
  "submittedHow": "web",
  "subject": "GRB 250509A: Swift-BAT refined analysis",
  "circularId": 40456,
  "format": "text/plain",
  "bibcode": "2025GCN.40456....1P",
  "createdOn": 1747191441105,
  "eventId": "GRB 250509A"
}