{
  "bibcode": "2009GCN.10114....1B",
  "body": "Aurelien Bouvier (SLAC), Julie McEnery (NASA/GSFC), Jim Chiang  \n(SLAC), Dan Kocevski (SLAC), Elena Moretti (INFN Trieste), Vlasios  \nVasileiou (NASA/GSFC & UMBC) and Frederic Piron (LPTA) report on  \nbehalf of the Fermi LAT team:\n\nWe present the flux and fluence upper limits based on the non- \ndetection of GRB 091024 (trigger 278067360 / 091024372) by the Fermi  \nLarge Area Telescope (Fermi LAT) in the 0.1-300 GeV energy range.  \nThis burst was detected by Swift (GCN 10062) and the Fermi Gamma-ray  \nBurst Monitor with a first emission interval lasting ~50 sec and a  \nsecond emission interval starting ~630 sec after trigger and lasting  \nmore than 400 sec (GCN 10070). The spacecraft performed a repointing  \nmaneuver for this burst which resulted in pointed observation for 5  \nhours starting ~350 sec after trigger.\nNo significant emission was detected in the LAT energy range during  \nany of the time intervals in which the burst was in the LAT field of  \nview. We computed the 95% CL upper limits using a bayesian method  \n(Helene O., 1983, N.I.M. 212, 319) and our background estimation tool  \n(described in Abdo et al. 2009: arXiv:0910.4192) on the LAT energy  \nflux and fluence for the time interval T0+350 to T0+2000 sec with  \nrespect to the GRB trigger time T0 (08:55:58.47 UT, October 24th  \n2009) and with an assumed spectral index of -2.2:\n- 95% Energy Flux Upper Limit = 9.4e-10 erg/cm^2/sec\n- 95% Energy Fluence Upper Limit = 1.5e-6 erg/cm^2\nThe upper limit results presented above are preliminary; final  \nresults will be published in the Fermi LAT GRB Catalog. The Fermi LAT  \nis a pair conversion telescope designed to cover the energy band from  \n20 MeV to greater than 300 GeV. It is the product of an international  \ncollaboration between NASA and DOE in the U.S. and many scientific  \ninstitutions across France, Italy, Japan and Sweden.",
  "circularId": 10114,
  "createdOn": 1256930948000,
  "email": "bouvier@slac.stanford.edu",
  "subject": "GRB 091024: Fermi LAT upper limits",
  "submitter": "Aurelien Bouvier at Stanford  <bouvier@slac.stanford.edu>",
  "eventId": "GRB 091024"
}