TITLE: GCN CIRCULAR NUMBER: 34851 SUBJECT: IceCube-231004A: Upper limits from Fermi-GBM Observations DATE: 23/10/20 15:50:36 GMT FROM: Joshua Wood at NASA/MSFC <joshua.r.wood@nasa.gov> J. Wood (NASA/MSFC), Eric Burns (LSU), Michelle Hui (NASA/MSFC) report on behalf of the Fermi-GBM team: For the IceCube high-energy neutrino candidate event IceCube-231004A (GCN 34797), at the event time Fermi-GBM was observing the reported neutrino location at: RA: 143.79 (+1.10, -1.01 deg 90% PSF containment) J2000 Dec: -25.04 (+1.03, -1.21 deg 90% PSF containment) J2000 There was no Fermi-GBM onboard trigger around the event time of the neutrino candidate. An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM also identified no counterpart candidates. The GBM targeted search, the most sensitive, coherent search for GRB-like signals, was run from +/-30 s around the neutrino candidate time. From this search, no significant signal was found related to IceCube-231004A. We set upper limits on impulsive gamma-ray emission to aid theoretical modeling of the potential optical counterpart AT2023uqf/ZTF23abidzvf (GCN 34837). Using the representative soft, normal, and hard GRB-like templates described in arXiv:2308.13666, we set the following 3 sigma flux upper limits over 10-1000 keV (in units of 10^-7 erg/s/cm^2): Timescale Soft Normal Hard ------------------------------------------- 0.128 s: 2.9 4.2 7.3 1.024 s: 0.9 1.4 2.3 8.192 s: 0.3 0.4 0.6 Assuming the reported redshift z = 0.1503 (GCN 34837), we estimate the following intrinsic luminosity upper limits over the 1 keV-10 MeV energy range (in units of 10^49 erg/s): Timescale Soft Normal Hard ------------------------------------ 0.128s: 2.8 3.7 10.6 1.024s: 0.8 1.2 3.3 8.192s: 0.3 0.3 0.9 These results are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/34851. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...