TITLE: GCN CIRCULAR NUMBER: 26368 SUBJECT: LIGO/Virgo S191205ah: No neutrino candidates at Pierre Auger Observatory DATE: 19/12/06 22:44:38 GMT FROM: Jaime Alvarez-Muniz at Pierre Auger Observatory J. Alvarez-Muniz, F. Pedreira, E. Zas (IGFAE & University of Santiago de Compostela, Spain), K. H. Kampert & M. Schimp (University of Wuppertal, Germany) on behalf of the Pierre Auger Collaboration. In response to: LIGO/Virgo GW trigger S191205ah T0=2019-12-05 21:52:08 UTC We searched for Ultra-High-Energy (UHE) neutrinos with energies above ~ 1e17 eV in data collected with the Surface Detector (SD) of the Pierre Auger Observatory in a [-500,500] second interval about the LIGO-Virgo trigger S191205ah as well as in a 24 hr time interval following the event. NO events survived the cuts applied to reject the background due to UHE Cosmic Rays i.e. NO neutrino candidates were detected. The field of view (fov) where the SD of Auger is sensitive to UHE neutrinos (corresponding to inclined directions with respect to the vertical relative to the ground) was PARTIALLY COINCIDENT (15.6%) with the LIGO/Virgo 90% localization region (bayestar.fits.gz,1) at the time T0 of the merger alert, achieving a MAXIMUM OVERLAP (50.2%) at approximately T0+5.73 hours. ------- The Pierre Auger Observatory is an UHE Cosmic Ray detector located in the Mendoza Province in Argentina. It consists of an array of Water Cherenkov detectors spread over a total surface of 3000 km^2 arranged in a triangular grid of 1.5 km side as well as Fluorescence telescopes and other systems (see 10.1016/j.nima.2015.06.058 for more information). For neutrino searches with Auger, please refer to: https://iopscience.iop.org/article/10.1088/1475-7516/2019/10/022 https://iopscience.iop.org/article/10.1088/1475-7516/2019/11/004