{
  "circularId": 40356,
  "eventId": "GRB 250430A",
  "submitter": "Mike Moss at NASA GSFC <mikejmoss3@gmail.com>",
  "body": "M. J. Moss (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), D. M. Palmer (LANL),\nT. Parsotan (GSFC), D. Sadaula (GSFC/UMBC),\nT. Sakamoto (AGU) (i.e. the Swift-BAT team):\n \nUsing the data set from T-61 to T+242 sec from the recent telemetry downlink,\nwe report further analysis of BAT GRB 250430A (trigger #1308754)\n(Parsotan, et al., GCN Circ. 40292).  The BAT ground-calculated position is\nRA, Dec = 233.395, -18.101 deg which is \n   RA(J2000)  =  15h 33m 34.7s \n   Dec(J2000) = -18d 06' 03.2\" \nwith an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment).\nThe partial coding was 72%.\n \nThe mask-weighted light curve displays a double peaked structure.\nThe T90 (15-350 keV) is 9.17 +- 1.70 sec (estimated error including systematics).\n \nThe time-averaged spectrum from T+0.10 to T+11.86 sec is best fit by a simple\npower-law model.  The power law index of the time-averaged spectrum is\n1.66 +- 0.11.  The fluence in the 15-150 keV band is 8.9 +- 0.6 x 10^-07 erg/cm2.\nThe 1-sec peak photon flux measured from T+0.31 sec in the 15-150 keV band\nis 2.3 +- 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/1308754",
  "format": "text/plain",
  "bibcode": "2025GCN.40356....1M",
  "submittedHow": "web",
  "createdOn": 1746499820779,
  "subject": "GRB 250430A: Swift-BAT refined analysis"
}