TITLE: GCN CIRCULAR NUMBER: 21248 SUBJECT: LIGO/Virgo G288732: HAWC follow-up DATE: 17/06/11 21:27:45 GMT FROM: Andrew Smith at U Maryland A.J. Smith (University of Maryland, College Park) and I. Martinez-Castellanos (University of Maryland, College Park) on behalf of the HAWC Collaboration: HAWC performed a follow-up of LIGO trigger G288732. At the time of the trigger (2017-06-08 02:01:16 UTC) there was no overlap between HAWC field of view (FOV) and the LIGO Bayester probability contour, so it was not possible to perform a coincidence search in short time scales. The LIGO contour entered HAWC FOV at around 2017-06-09 16:00 UTC and left it ~8hr later. The most probable location reached a zenith angle of ~10deg at culmination. We integrated this period for a total exposure of ~6hrs on each location of the ~70% of the LIGO probability contour observed. There were no significant detections. Using this same integration period we followed-up the weak candidate reported by the Fermi-LAT team (R.A.,Dec.=128.11, 43.3, GCN circular 21227). The most significant location 2deg around the Fermi LAT trigger corresponds to 2.1 standard deviations pre-trials (R.A.,Dec.=128.4, 42.72). We set a 95% upper-limit in this location of 4.6e-11 (E/1TeV)^-2.5 TeV^-1 cm^-2 s^-1. HAWC is a TeV gamma ray water Cherenkov array located in the state of Puebla, Mexico. It is sensitive to the energy range ~0.5-100TeV, and monitors 2/3 of the sky every day with an instantaneous field-of-view of ~2 sr.