{
  "bibcode": "2013GCN.15268....1K",
  "body": "D. Kocevski, J. Racusin (NASA/GSFC), G. Vianello (Stanford), M. Axelsson\n(Stockholm University), Nicola Omodei (Stanford) report on behalf of the\nFermi-LAT team:\n\nA preliminary examination of the Fermi LAT data of the field containing GRB\n130925A (Lien, et al., GCN 15246) has revealed no significant emission\nabove 40 MeV. The GRB was located ~22 degrees away from the LAT boresight\nat the time of the first GBM detected emission associated with this burst\nat 03:56:23.29 UT on 25 September 2013 (GCN 15255), hereafter T0(GBM), and\nthe subsequent autonomous repoint ensured that the source remained in the\nfield-of-view for the next ~2000s until it was occulted by the Earth.\n\nUsing an unbinned likelihood analysis, we estimate the following LAT upper\nlimits at 95% confidence for three separate time intervals, one covering\nthe entire 2000s that the source stayed in the LAT field-of-view, and two\nof which correspond to the first and third emission episodes detected by\nINTEGRAL/SPI-ACS (GCN 15259) and Konus-Wind (GCN 15260). We note that the\nsource was not in the LAT field-of-view during the second interval reported\nin GCNs 15259 & 15260.\n\nInterval 1: T0(GBM) to T0(GBM)+2000 = 7.3e-07 photons cm-2 s-1 (4.8e-10\nergs cm-2 s-1)\nInterval 2: T0(GBM)+900s to T0(GBM)+1100s = 5.5e-06 photons cm-2 s-1\n(3.6e-09 ergs cm-2 s-1)\nInterval 3: T0(GBM)+4900 to T0(GBM)+5400 = 2.5e-06 photons cm-2 s-1\n(1.6e-09 ergs cm-2 s-1)\n\nThis analysis covers an energy range of 0.1 to 10 GeV with a 12 deg\nextraction region centered on the best known source position (GCN 15246).\n The upper limits are computed using the P7SOURCE_V6 instrument response\nfunctions, where we assume a power-law source spectrum fixed to a photon\nindex of -2.1, reflecting a typical value for high-energy emission in GRBs.\nFor reference, T0(GBM) = T0(BAT)-900s.\n\nThe Fermi LAT point of contact for this burst is Magnus Axelsson (\nmagnusa@astro.su.se).\n\nThe Fermi LAT is a pair conversion telescope designed to cover the energy\nband from 20 MeV to greater than 300 GeV. It is the product of an\ninternational collaboration between NASA and DOE in the U.S. and many\nscientific institutions across France, Italy, Japan and Sweden.",
  "circularId": 15268,
  "createdOn": 1380326592000,
  "email": "dankocevski@gmail.com",
  "subject": "Fermi LAT Upper Limits on GRB 130925A",
  "submitter": "Daniel Kocevski at SLAC  <dankocevski@gmail.com>",
  "eventId": "GRB 130925A"
}