TITLE: GCN CIRCULAR NUMBER: 35784 SUBJECT: Swift BAT Sub-Threshold Detection of EPW20240219aa DATE: 24/02/23 19:20:28 GMT FROM: Jimmy DeLaunay at Penn State <delauj2@gmail.com> James DeLaunay (PSU), Aaron Tohuvavohu (U Toronto), Samuele Ronchini (PSU), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report: Swift/BAT did not localize EPW20240219aa onboard (ATel 16463; ATel 16472). In a ground analysis of a 300 s BAT survey exposure starting at 2024-02-19T06:18:06 we find a source matching the position of EPW20240219aa at a SNR of 5.4. The BAT position is RA, Dec = 80.046, +25.500 deg which is RA(J2000) = 05h 20m 11.04s Dec(J2000) = +25d 30′ 00.0″ with an estimated uncertainty of 4 arcmin radius. An inspection of the BAT rates data shows this burst starting at ~2024-02-19T06:21:44 and lasting ~55 s, matching the observation by Fermi GBM (GCN 35773, GCN 35776). With the observation by BAT that matches spatially and temporally we conclude that EPW20240219aa is most likely a GRB. View this GCN Circular online at https://gcn.nasa.gov/circulars/35784. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...