{
  "bibcode": "2012GCN.13379....1V",
  "body": "Giacomo Vianello (CIFS/SLAC), Daniel Kocevski (Stanford Univ.) report\non behalf of the Fermi LAT Team:\n\nFermi-LAT has detected high energy emission from the long, hard and\nbright GRB 120624B in ground analysis. The GRB was triggered on by the\nGBM on June 24, 2012 at 22:23:54.93 UTC, although the emission started\n~250 seconds earlier (trigger 362269436, GCN 13377).\n\nThe best GBM position was \\~70 deg off-axis for the whole duration of\nthe prompt emission (~270 seconds), outside of the Fermi/LAT nominal\nfield of view for the standard data analysis.\n\nUsing a non-standard data selection most sensitive in the tens-of-MeV\nenergy range and with a broader acceptance, we significantly detected\nthe burst between ~T0-250s and ~T0+20 s. The significance of the\nexcess corresponds to 10 sigma. The light curve shows 3 peaks, with a\ntotal duration of \\~270 s.\n\nThis burst was bright enough to result in a Fermi spacecraft\nautonomous rapid repoint (ARR) maneuver, starting 100 s after the GBM\ntrigger. Thus, the GBM position entered the LAT field of view at\n\\~T0+100 s.\n\nA preliminary maximum-likelihood analysis of the E>100MeV\nP7TRANSIENT_V6 LAT data generated during the interval T0+100, T0+1.3\nks (until the GRB became occulted by the Earth) revealed a very\nsignificant transient source, with a spectrum well described by a\npower law of index -2.4 +/- 0.1 (68% c.l. statistical only). Using\nthis analysis, we obtained the best LAT on-ground localization of:\n\nRA(J2000) = 170.73 deg\nDec(J2000) = 9.48 deg\n\nwith an error radius 0.45 deg (90% containment, statistical error\nonly), which is 3.6 deg from the best GBM localization.\n\nThe Zenith angle for this source was ~30 deg at the time of the\ntrigger, thus very far from the Earth Limb.\n\nA Swift/ToO request has been submitted.\n\nThe Fermi-LAT point of contact for this burst is Daniel Kocevski\n(kocevski@stanford.edu)",
  "circularId": 13379,
  "createdOn": 1340619527000,
  "email": "giacomov@slac.stanford.edu",
  "subject": "GRB 120624B: Fermi-LAT Detection",
  "submitter": "Giacomo Vianello at SLAC  <giacomov@slac.stanford.edu>",
  "eventId": "GRB 120624B"
}