{
  "bibcode": "1999GCN...448....1G",
  "body": "GRB991106: BeppoSAX/BATSE results\n\nG. Gandolfi and P. Soffitta (IAS/CNR,Roma), J. Heise and J. in 't Zand\n(SRON, Utrecht), L.Amati (ITESRE/CNR, Bologna) on behalf of BeppoSAX GRB\nTeam and R. M. Kippen and P. M. Woods (University of Alabama in\nHuntsville) and C. A. Meegan (NASA/MSFC) on behalf of the BATSE GRB team\nreport:\n\nThe BeppoSAX 4-sigma detection ((9.5 +/- 2.4)E-8 erg/cm2/s in the\n40-700 keV range) of a short gamma peak of about 1 s of duration in\ncorrespondence with the X-ray transient reported in GCN 443 (GRB991106)\nwas not confirmed by BATSE observations. The WFC source position was\nobservable to BATSE (i.e., not occulted by the earth). The on-board\ntrigger was disabled, but the continuous data with 1.024 and 4.096 second\nresolution shows no evidence for significant excess flux above background.\nUpper limits (2-sigma), based on these data are:\n\n   F < 6.6e-9 erg/cm^2/s  (25- 50 keV)\n   F < 1.7e-8 erg/cm^2/s  (50-300 keV)\n   F < 2.7e-8 erg/cm^2/s  (40-700 keV; the BeppoSAX GRBM energy range)\n\nWe therefore conclude that the BeppoSAX-GRBM detection was apparently\neither a statistical fluctuation or a spurious event of a different origin\n(e.g. Cosmic Rays).\nOn the other side, the faint WFC X-ray transient, with a (2.0 +/- 0.4)E-8\nerg/cm2/s peak flux in the 2-26 keV range, shows marginal evidence\nof a high hardness ratio.\nThese BeppoSAX/BATSE combined results suggest a peculiarly short and\nhard X-ray burst or an anomalous GRB. The lower limit to the ratio of\nX-ray to gamma peak flux is about 0.75, a factor 5 higher\nthan average values found for BeppoSAX prompt GRB counterparts,\nindicating in the latter case a X-ray rich event, i.e. a candidate member\nof the X-ray-GRB class.",
  "circularId": 448,
  "createdOn": 942490209000,
  "email": "gandolfi@ias.rm.cnr.it",
  "subject": "GRB991106: BeppoSAX/BATSE results",
  "submitter": "Giangiacomo Gandolfi at IAS/CNR Frascati  <gandolfi@ias.rm.cnr.it>",
  "eventId": "GRB 991106"
}