TITLE:   GCN CIRCULAR
NUMBER:  24523
SUBJECT: LIGO/Virgo S190513bm: HAWC follow-up
DATE:    19/05/13 21:48:56 GMT
FROM:    Hugo Ayala at Pennsylvania State University  <hgayala@psu.edu>

The HAWC Collaboration (https://www.hawc-observatory.org) reports:The
HAWC Collaboration performed a follow-up of the gravitational
wavetrigger S190513bm. At the time of the trigger the HAWClocal zenith
was oriented towards (RA, Dec) = (87.4deg, 19.0deg).46% of the GW
candidate sky location probability fell within ourobservable field of
view (0-45 deg zenith angle).We performed a search for a short
timescale emission using 6 slidingtime windows (dt = 0.3s, 1s, 3s,
10s, 30s and  100s), shifted forwardin time by 20% of their width. We
searched the 95% probabilitycontainment area in a timescale-dependent
time period, from t0-5dt tot0+10dt, where t0 is the time of the GW
trigger.No significant gamma-ray detection above the background was
observed.The sensitivity of this analysis is greatly dependent on
zenith angle,ranging from 33.3deg to 45.0deg for the area searched in
thisanalysis. The 5sigma detection sensitivity to a 1s (100s) burst in
the80-800GeV energy range goes from 1.1e-05 erg/cm^2 to 1.1e-04
erg/cm^2(5.4e-05 erg/cm^2 to 5.0e-04 erg/cm^2), depending on the
zenithangle.HAWC is a TeV gamma ray water Cherenkov array located in
the state ofPuebla, Mexico. It is sensitive to the energy range
~0.1-100TeV, andmonitors 2/3 of the sky every day with an
instantaneous field-of-viewof ~2 sr.