TITLE: GCN CIRCULAR NUMBER: 41233 SUBJECT: GRB 250805A: Swift detection of a burst DATE: 25/08/05 06:26:15 GMT FROM: Elena Ambrosi at INAF-IASF elena.ambrosi@inaf.it

E. Ambrosi (INAF-IASFPA), S. Dichiara (PSU), R. Gupta (NASA GSFC), K. L. Page (U Leicester) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:

At 06:09:08 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250805A (trigger=1339848). The BAT on-board calculated location is RA, Dec 24.153, -81.406 which is RA(J2000) = 01h 36m 37s Dec(J2000) = -81d 24' 22" 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 30 sec. The peak count rate was ~1800 counts/sec (15-350 keV), at ~0 sec after the trigger.

Due to an observing constraint, Swift will not slew until ~ 57 minutes. There will be no XRT or UVOT data until this time.

Burst Advocate for this burst is E. Ambrosi (elena.ambrosi AT inaf.it). 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/)

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