TITLE: GCN CIRCULAR NUMBER: 29086 SUBJECT: GRB201216C: No significant detection in HAWC DATE: 20/12/18 17:04:28 GMT FROM: Hugo Ayala at Pennsylvania State University On 2020/12/16 at 23:07:31 UTC, following the trigger by Swift-BAT and Fermi-GBM (GCN 29061, GCN 29063), HAWC observed the position of GRB 201216C. The position of the GRB at the time of trigger (t0) fell just inside the field of view of HAWC, at 40 deg from zenith. We observed the position in the time range [t0-100s,t0+3600s]. At the end of the analysis, the position was at 25 deg from zenith. We scanned this range with time bins of 100s width. The time window advances every 20s, producing 80% overlap between different time windows. No emission was observed. The most conservative flux upper-limit at 95% C.L. measured during the time range is dN/dE = 4.05e-10 (E/TeV)^-2.0 [TeV^-1 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.