{
  "bibcode": "2020GCN.27368....1K",
  "body": "M. Kovacevic (INFN Perugia), M. Ohno (Hiroshima University), M. Axelsson\n(KTH & Stockholm Univ),\nE. Bissaldi (Politecnico & INFN Bari), D. Kocevski (NASA/MSFC), N. Omodei\n(Stanford Univ.), N. Di Lalla (Stanford Univ.) and\nF. Longo (University and INFN, Trieste) report on behalf of the Fermi-LAT\nCollaboration:\n\n\nWe have searched data collected by the Fermi Large Area Telescope (LAT) on\nMarch 11, 2020, for possible high-energy (E > 100 MeV) gamma-ray emission\nin\nspatial/temporal coincidence with the LIGO/Virgo trigger S200311bg (GCN\n27358).\n\nWe define \"instantaneous coverage\" as the integral over the region of the\nLIGO\nprobability map that is within the LAT field of view at a given time,\nand \"cumulative\ncoverage\" as the integral of the instantaneous coverage over time.\n\nThe Fermi Gamma-ray Space Telescope was passing through the South Atlantic\nAnomaly (SAA)\nat the time of the trigger (T0 = 2020-03-11 11:58:53.398 UTC). During SAA\npassages both the LAT\nand the Gamma-ray Burst Monitor (GBM) do not collect data due to the high\ncharged particle\nbackground in this region.\n\nThe LAT resumed taking data upon exiting the SAA at roughly T0 + 1.6 ks.\n\nAt that time the instantaneous coverage was 100% of the LIGO probability\nmap, therefore\n100% cumulative coverage was reached at that time as well.\n\nWe performed a search for a transient counterpart within the observed\nregion of\nthe 90% contour of LIGO map in  a fixed time window from T0 + 1.6 ks to T0\n+ 10 ks.\nNo significant new sources are found.\n\nWe also performed a search which adapted the time interval of the analysis\nto the\n\nexposure of each region of the sky, and no additional excesses were found.\n\nEnergy flux upper bounds for the fixed time interval between 100 MeV and 1\nGeV\nfor this search vary between 8.0e-10 and 1.1e-8 [erg/cm^2/s].\n\nThe Fermi-LAT point of contact for this event is\nMilos Kovacevic (milos.kovacevic@pg.infn.it).\n\nThe Fermi-LAT is a pair conversion telescope designed to cover\nthe energy band from 20 MeV to greater than 300 GeV.\nIt is the product of an international collaboration between\nNASA and DOE in the U.S. and many scientific institutions\nacross France, Italy, Japan and Sweden.",
  "circularId": 27368,
  "createdOn": 1583970036000,
  "email": "ohno@astro.hiroshima-u.ac.jp",
  "subject": "LIGO/Virgo S200311bg: No significant counterpart candidates in Fermi-LAT observations",
  "submitter": "Masanori Ohno at Hiroshima University  <ohno@astro.hiroshima-u.ac.jp>",
  "eventId": "LIGO/Virgo S200311bg"
}