{
  "circularId": 35861,
  "subject": "Swift J151857.0-572147: Swift-BAT refined analysis",
  "submitter": "Amy <yarleen@gmail.com>",
  "body": "S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC),\nH. A. Krimm (NSF), A. Y. Lien (U Tampa),\nC. B. Markwardt (GSFC), M. J. Moss (GSFC),\nD. M. Palmer (LANL), T. Parsotan (GSFC),\nT. 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,\nwe report further analysis of Swift J151857.0-572147 (trigger #1218452)\n(Lien et al., GCN Circ. 35849).  The BAT ground-calculated position is\nRA, Dec = 229.773, -57.364 deg which is\n   RA(J2000)  =  15h 19m 05.5s\n   Dec(J2000) = -57d 21' 50.8\"\nwith an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).\nThe partial coding was 86%.\n\nThe mask-weighted light curve shows a consistent emission throughout\nthe entire time interval when the source was in the BAT FOV from\nT-127 s to T+798 s. In addition, BAT triggered on this source\nagain on March 4th at 08:53 UT (Ambrosi et al., GCN Circ. #35858),\nindicating that the source is still detectable in BAT.\nThe BAT transient monitor shows that the source started to\nappear on March 3rd.\n\nThe time-averaged spectrum from T-83.64 to T+753.64 sec is best\nfit by a power law with an exponential cutoff.  This fit gives\na photon index 1.72 +- 0.44, and Epeak of 14.0 +- 10.1 keV\n(chi squared 72.90 for 56 d.o.f.).  For this model the total\nfluence in the 15-150 keV band is 5.7 +- 0.4 x 10^-6 erg/cm2\nand the 1-sec peak flux measured from T-80.60 sec in the\n15-150 keV band is 0.4 +- 0.2 ph/cm2/sec.  A fit to a simple\npower law gives a photon index of 2.48 +- 0.11 (chi squared 79.64\nfor 57 d.o.f.).  All the quoted errors are at the 90% confidence level.\n\nThe results of the batgrbproduct analysis are available at\nhttps://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1218452\n\nThe BAT transient monitor page for this source will be available at\nhttps://swift.gsfc.nasa.gov/results/transients/weak/SwiftJ1518-5721/\n",
  "submittedHow": "email",
  "bibcode": "2024GCN.35861....1L",
  "createdOn": 1709577302381
}