{
  "bibcode": "2021GCN.29266....1S",
  "body": "T. Sakamoto (AGU), S. D. Barthelmy (GSFC),\nH. A. Krimm (NSF), S. Laha (GSFC/UMBC),\nA. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),\nD. M. Palmer (LANL), M. Stamatikos (OSU),\nT. N. Ukwatta (LANL) (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 210104B (trigger #1015919)\n(Laha et al., GCN Circ. 29243).  The BAT ground-calculated position is\nRA, Dec = 53.561, 37.951 deg which is\n   RA(J2000)  =  03h 34m 14.7s\n   Dec(J2000) = +37d 57' 05.1\"\nwith an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).\nThe partial coding was 59%.\n\nThe mask-weighted light curve shows a double peaks structure that starts\nat ~T0 and ends at ~T+23 s. The two peaks occurs at ~T0 and ~T+11 s,\nrespectively. T90 (15-350 keV) is 19.94 +- 2.33 sec (estimated error\nincluding systematics).\n\nThe time-averaged spectrum from T-0.15 to T+22.76 sec is best fit\nby a simple power-law model.  The power law index of the time-averaged\nspectrum is 1.83 +- 0.14.  The fluence in the 15-150 keV band is\n1.2 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from\nT+10.83 sec in the 15-150 keV band is 1.9 +- 0.3 ph/cm2/sec.  All the\nquoted errors are at the 90% confidence level.\n\nThe results of the batgrbproduct analysis are available at\nhttp://gcn.gsfc.nasa.gov/notices_s/1015919/BA/",
  "circularId": 29266,
  "createdOn": 1609889230000,
  "email": "amy.y.lien@nasa.gov",
  "subject": "GRB 210104B: Swift-BAT refined analysis",
  "submitter": "Amy Lien at GSFC  <amy.y.lien@nasa.gov>",
  "eventId": "GRB 210104B"
}