TITLE: GCN CIRCULAR NUMBER: 34805 SUBJECT: IceCube-231004A: No significant detection in HAWC DATE: 23/10/05 19:38:31 GMT FROM: Hugo Ayala at Pennsylvania State University <hgayala@psu.edu> Hugo Ayala (PSU) reports on behalf of the HAWC collaboration (http://www.hawc-observatory.org/collaboration): On 2023/10/04 14:39:41.18 UTC, the IceCube collaboration reported a track-like very-high-energy event that has a high probability of being an astrophysical neutrino, IceCube-231004A. Location is 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 (GCN circular 34791,34792). We performed two types of analyses for the follow-up. The first is for a steady source in archival data and the second is a search for a transient source. We assume a power-law spectrum with an index of -2.3 for both analyses. Search for a steady source in archival data: The archival data spans from November 2014 to October 2021. We searched inside the reported IceCube error region. The most significant location, with p-value 2.19e-03 (5.13e-02 post-trials), is at RA 144.67 deg, Dec +24.91 deg (±0.42 deg 68% containment) J2000. We set a time-integrated 95% CL upper limit on gamma rays at the maximum position of: E^2 dN/dE = 1.11e-13 (E/TeV)^-0.3 TeV.cm^-2.s^-1 Search for a transient source. Since the IceCube event fall inside the HAWC field of view, we report on the result for the transit of the IceCube position. Data acquisition started on 2023/10/04 06:13:44 UTC and ended 2023/10/04 18:28:44 UTC. The most significant location, with p-value 3.14e-02 (0.53 post-trials), is at RA 143.17 deg, Dec +24.79 deg (±0.26 deg 68% containment) J2000. We set a time-integrated 95% CL upper limit at the position of maximum significance of: E^2 dN/dE = 1.67e-11 (E/TeV)^-0.3 TeV.cm^-2.s^-1 HAWC is a very-high-energy gamma-ray observatory operating in Central Mexico at latitude 19 deg. north. Operating day and night with over 95% duty cycle, HAWC has an instantaneous field of view of 2 sr and surveys 2/3 of the sky every day. It is sensitive to gamma rays from 300 GeV to 100 TeV. View this GCN Circular online at https://gcn.nasa.gov/circulars/34805. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...