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.