{
  "bibcode": "2020GCN.27613....1L",
  "body": "Alexander Lutovinov (IKI, Russia),�� Enrico Bozzo,\nV. Savchenko, C. Ferrigno (ISDC/UniGE, Switzerland)\nJ. Rodi (IAPS-Roma, Italy)\nA. Coleiro (APC, France)\nS. Mereghetti (INAF IASF-Milano, Italy)\n\non behalf of the INTEGRAL multi-messenger collaboration:\nhttps://www.astro.unige.ch/cdci/integral-multimessenger-collaboration\n\nUsing combination of INTEGRAL all-sky detectors (following [1]):\nSPI/ACS, IBIS/Veto, and IBIS we have performed a search for a prompt\ngamma-ray counterpart of unknown (GCN 27612).\n\nAt the time of the event (2020-04-21 00:35:24 UTC, hereafter T0),\nINTEGRAL was operating in nominal mode. The peak of the event\nlocalization probability was at an angle of 162 deg with respect to\nthe spacecraft pointing axis. This orientation implies strongly\nsuppressed (3.7% of optimal) response of ISGRI, near-optimal (85% of\noptimal) response of IBIS/Veto, and strongly suppressed (38% of\noptimal) response of SPI-ACS.\n\nThe background within +/-300 seconds around the event was rather\nstable (excess variance 1.3).\n\nWe have performed a search for any impulsive events in INTEGRAL SPI-\nACS (as described in [2]), IBIS, and IBIS/Veto data.\n\nWe do not detect any significant counterparts and estimate a 3-sigma\nupper limit on the 75-2000 keV fluence of 4.9e-07 erg/cm^2 (within the\n50% probability containment region of the source localization) for a\nburst lasting less than 1 s with a characteristic short GRB spectrum\n(an exponentially cut off power law with alpha=-0.5 and Ep=600 keV)\noccurring at any time in the interval within 300 s around T0. For a\ntypical long GRB spectrum (Band function with alpha=-1, beta=-2.5, and\nEp=300 keV), the derived peak flux upper limit is ~5e-07 (9.2e-08)\nerg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range.\n\nWe report for completeness and in order of FAP, all excesses\nidentified in the search region. We find: 2 possibly associated\nexcesses:\n\nT-T0 | scale | S/N | flux ( x 1e-06 erg/cm2/s) | FAP\n3.07 | 1.15 | 3.6 | 0.553 +/- 0.152 +/- 0.186 | 0.0163\n40 | 9.5 | 3.5 | 2.09 +/- 0.526 +/- 0.703 | 0.033\n\n2 likely background excesses:\n\nT-T0 | scale | S/N | flux ( x 1e-06 erg/cm2/s) | FAP\n-36.6 | 1.5 | 3.3 | 0.433 +/- 0.133 +/- 0.146 | 0.307\n-119 | 0.35 | 4.6 | 1.25 +/- 0.277 +/- 0.419 | 0.668\nAll results quoted are preliminary.\n\nThis circular is an official product of the INTEGRAL Multi-Messenger\nteam.\n\n[1] Savchenko et al. 2017, A&A 603, A46 [2] Savchenko et al. 2012, A&A\n541A, 122S",
  "circularId": 27613,
  "createdOn": 1587465017000,
  "email": "aal@iki.rssi.ru",
  "subject": "IceCube-200421A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation",
  "submitter": "Alexander Lutovinov at Space Research Inst.,IKI  <aal@iki.rssi.ru>",
  "eventId": "IceCube-200421A"
}