TITLE:   GCN CIRCULAR
NUMBER:  25626
SUBJECT: LIGO/Virgo S190901ap: No neutrino candidates at Pierre Auger Observatory
DATE:    19/09/03 09:00:45 GMT
FROM:    Jaime Alvarez-Muniz at Pierre Auger Observatory  <jaime.alvarezmuniz@gmail.com>

J. Alvarez-Muniz, F. Pedreira, E. Zas (Univ. Santiago de Compostela, Spain),
K. H. Kampert & M. Schimp (Bergische Universitat, Wuppertal, Germany)
on behalf of the Pierre Auger Collaboration.

In response to:
LIGO/Virgo GW trigger S190901ap
T0=2019-09-01 23:31:01 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 S1900901ap as well as 1 day after it.

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 (38.7%) with
the LIGO/Virgo 90% localization region (LALInference.v2.fits.gz)
at the time T0 of the merger alert, achieving MAXIMUM OVERLAP (47.7%)
at approximately T0+17.2 hours

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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 from GW events with Auger, please refer to:
https://journals.aps.org/prd/pdf/10.1103/PhysRevD.94.122007
https://arxiv.org/abs/1906.07422