TITLE: GCN CIRCULAR NUMBER: 42843 SUBJECT: GRB 251126A: Swift detection of a burst DATE: 25/11/26 19:26:44 GMT FROM: K.L. Page at U Leicester <klp5@leicester.ac.uk> R. Caputo (GSFC), M. J. Moss (GSFC), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team: At 19:10:36 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 251126A (trigger=1417793). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 99.910, +54.987 which is RA(J2000) = 06h 39m 39s Dec(J2000) = +54d 59' 13" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 20 sec. The peak count rate was ~2600 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 19:11:58.3 UT, 81.7 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 99.94124, 54.98591 which is equivalent to: RA(J2000) = 06h 39m 45.90s Dec(J2000) = +54d 59' 09.3" with an uncertainty of 4.4 arcseconds (radius, 90% containment). This location is 64 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. No spectrum from the promptly downlinked event data is yet available to determine the column density. There are no UVOT data available at this time. Analysis will be reported at a later time. Burst Advocate for this burst is R. Caputo (regina.caputo AT nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) View this GCN Circular online at https://gcn.nasa.gov/circulars/42843. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...