{
"subject": "IceCube-200107A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation",
"bibcode": "2020GCN.26666....1C",
"createdOn": 1578482919000,
"circularId": 26666,
"submitter": "Alexis Coleiro at APC/U. Paris Diderot ",
"email": "coleiro@apc.in2p3.fr",
"body": "Alexis Coleiro (APC, France), Carlo Ferrigno (ISDC/UniGE, Switzerland),\nV. Savchenko (ISDC/UniGE, Switzerland),\nJ. Rodi (IAPS-Roma, Italy),\nS. Mereghetti (INAF IASF-Milano, Italy)\non behalf of the INTEGRAL multi-messenger collaboration:\nhttps://www.astro.unige.ch/cdci/integral-multimessenger-collaboration\n\nUsing INTEGRAL/SPI-ACS realtime data (following [1]) we have performed\na search for a prompt gamma-ray counterpart of IceCube-200107A (GCN 26655).\nAt the time of the event (2020-01-07 09:42:18 UTC, hereafter T0),\nINTEGRAL was operating in nominal mode. The peak of the event\nlocalization probability was at an angle of 78 deg with respect to the\nspacecraft pointing axis. This orientation implies strongly suppressed\n(24% of optimal) response of ISGRI, strongly suppressed (40% of\noptimal) response of IBIS/Veto, and near-optimal (70% of optimal)\nresponse of SPI-ACS.\nThe background within +/-300 seconds around the event was somewhat\nunstable (excess variance 1.8).\nWe have performed a search for any impulsive events in INTEGRAL SPI-\nACS (as described in [2]) data (IBIS data are not considered since they are \nonly partially available in the search region due to the instrument starting the \nobservations after the perigee shortly before the IceCube trigger).\nWe do not detect any significant counterparts and estimate a 3-sigma\nupper limit on the 75-2000 keV fluence of 2.8e-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 ~2.4e-07 (1.2e-07)\nerg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range.\nWe report for completeness and in order of FAP, all excesses\nidentified in the search region. We find 4 likely background\nexcesses:\nT-T0 | scale | S/N | flux ( x 1e-06 erg/cm2/s) | FAP \n12.5 | 0.45 | 3.3 | 0.432 +/- 0.122 +/- 0.117 | 0.328 \n-64.5 | 0.9 | 3.4 | 3.33 +/- 0.863 +/- 0.9 | 0.663 \n-41.5 | 0.15 | 4.3 | 0.939 +/- 0.213 +/- 0.254 | 0.681 \n-86.8 | 1.3 | 3.3 | 2.75 +/- 0.717 +/- 0.743 | 0.76 \nNote that FAP estimates (especially at timescales above 2s) may be\nfurther affected by enhanced non-stationary local background\nnoise. This list excludes any excesses for which FAP is close to\nunity.\n\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\nGCN pipeline version: 88154a3\n\n\n������������������������������������������������������������������������������\nAlexis Coleiro\nMa��tre de conf��rences - Universit�� Paris Diderot\nLaboratoire Astroparticule et Cosmologie (APC)\n10 rue Alice Domon et L��onie Duquet\n75205 Paris Cedex 13 (France)\nTel.: +33 1 57 27 60 59 / coleiro@apc.univ-paris-diderot.fr"
}