TITLE: GCN CIRCULAR NUMBER: 24876 SUBJECT: Swift Trigger 911102: a possible GRB DATE: 19/06/24 21:03:50 GMT FROM: Amy Lien at GSFC S. B. Cenko (GSFC), J.D. Gropp (PSU), N. J. Klingler (PSU), A. Y. Lien (GSFC/UMBC), A. Melandri (INAF-OAB), D. M. Palmer (LANL), T. Sakamoto (AGU) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 20:40:40 UT, the Swift Burst Alert Telescope (BAT) triggered and located a possible GRB (trigger=911102). Swift did not slew immediately due to an observing constraint. The BAT on-board calculated location is RA, Dec 144.524, +46.476 which is RA(J2000) = 09h 38m 06s Dec(J2000) = +46d 28' 34" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is usual with an image trigger, the available BAT light curve shows no significant structure. Due to an observing constraint, Swift will not slew until T0+51 minutes. There will be no XRT or UVOT data until this time. Due to the marginal significance of this image trigger (7.2 sigma in on-board imaging, with a reduced significance in ground processing) and the lack of immediate XRT follow-up, we cannot yet confirm that this is an astrophysical event. The determination of the reality of this event will require the full downlinked dataset or the detection of the source in the XRT follow-up after it comes out of observing constraint. Burst Advocate for this burst is S. B. Cenko (brad.cenko 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/)