{
  "bibcode": "2017GCN.21611....1S",
  "body": "V. Savchenko (ISDC, University of Geneva, CH)\non behalf of the INTEGRAL group:\nS. Mereghetti (IASF-Milano, Italy),\nC. Ferrigno ((ISDC, University of Geneva, CH),\nE. Kuulkers (ESTEC/ESA, The Netherlands),\nA. Bazzano (IAPS-Roma, Italy), E. Bozzo,\nT. J.-L. Courvoisier (ISDC, University of Geneva, CH)\nS. Brandt (DTU - Denmark) R. Diehl (MPE-Garching, Germany)\nL. Hanlon (UCD, Ireland) P. Laurent (APC, Saclay/CEA, France)\nA. Lutovinov (IKI, Russia) J.P. Roques (CESR, France)\nR. Sunyaev (IKI, Russia) P. Ubertini (IAPS-Roma, Italy)\n\nWe investigated serendipitous INTEGRAL observations carried out at the\ntime of the LIGO/Virgo burst candidate G298389.  The satellite was\npointing at RA=193.46 Dec=-25.644, 43 degrees from far from the peak\nof high-probability area of LIGO localization. Depending on the\nlocation within LIGO 90% confidence region the best upper limit is set\nby the anti-coincidence shield of the spectrometer on board of\nINTEGRAL (SPI/ACS), IBIS/ISGRI, or IBIS/PICsIT. The localization of\nG298389 is not optimal for SPI-ACS observation, since part of the\nlocalization it is occulted for SPI-ACS by the coded mask of IBIS. For\nharder source spectra, IBIS, and especially IBIS/PICsIT reaches\nsensitivity close to optimal in this orientation.\n\nThe INTEGRAL IBAS automatically inspects both ISGRI Field\nof View and all-sky SPI-ACS light curve. It did not reveal any\nsignificant excess above the background.\n\nWe investigated the SPI-ACS, IBIS/PICsIT, and IBIS/ISGRI light curves\nbetween -500 and +500 s from the trigger time (2017-08-19 15:50:46\nUTC) on temporal scales from 0.1 to 100 s, and found no evidence for\nany significant deviation from the background.  We estimate a median\n3-sigma upper limits in 90% LIGO localization region of 1.9e-6 erg/cm2\n(75-2000 keV) assuming a duration of 8s and Band model parameters\nalpha=-1, beta=-2.5, and E_ peak = 300 keV.  To derive a limit for a\ntypical short burst with 1 s duration, we use a harder cutoff power\nlaw spectrum with a photon index of -0.5 and an Epeak = 500 keV. We\nfind a median limiting fluence of 4.0e-7 erg/cm2 (75-2000 keV) at 3\nsigma c.l.",
  "circularId": 21611,
  "createdOn": 1503217635000,
  "email": "savchenk@apc.in2p3.fr",
  "subject": "LIGO/Virgo G298389: INTEGRAL search for a prompt gamma-ray counterpart",
  "submitter": "Volodymyr Savchenko at APC,Paris  <savchenk@apc.in2p3.fr>",
  "eventId": "LIGO/Virgo G298389"
}