{
  "submitter": "Amy <yarleen@gmail.com>",
  "bibcode": "2025GCN.41598....1M",
  "createdOn": 1756509398599,
  "circularId": 41598,
  "submittedHow": "email",
  "body": "M. J. Moss (GSFC), S. D. Barthelmy (GSFC), R. Gupta (GSFC), P. A. Evans (U\nLeicester), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa),\nC. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula\n(GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team):\n\nUsing the data set from T-239 to T+963 sec from the recent telemetry\ndownlink, we report further analysis of BAT GRB 250828B (trigger #1345836)\n(Evans et al., GCN Circ. 41581).  The BAT ground-calculated position is\nRA, Dec = 124.867, -17.352 deg which is\n   RA(J2000)  =  08h 19m 28.2s\n   Dec(J2000) = -17d 21' 07.8\"\nwith an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The\npartial coding was 64%.\n\nThe mask-weighted light curve shows a complex structure. The main pulse\nstarts and peaks at ~T0, and ends at ~T+5 s. In addition, there are some\nweak emission that starts prior to the main pulse at ~T-60 s and persists\nafter the main pulse until ~T+60 s. T90 (15-350 keV) is 94.09 +- 32.03 sec\n(estimated error including systematics).\n\nThe time-averaged spectrum from T-56.23 to T+76.66 sec is best fit by a\nsimple power-law model.  The power law index of the time-averaged spectrum\nis 2.13 +- 0.19.  The fluence in the 15-150 keV band is 1.5 +- 0.2 x 10^-06\nerg/cm2. The 1-sec peak photon flux measured from T+0.12 sec in the 15-150\nkeV band is 1.7 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90%\nconfidence level.\n\nThe results of the batgrbproduct analysis are available at\nhttps://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1345836\n",
  "eventId": "GRB 250828B",
  "subject": "GRB 250828B: Swift-BAT refined analysis"
}