TITLE: GCN CIRCULAR NUMBER: 41115 SUBJECT: Swift Trigger 1334535: a possible GRB 250718A DATE: 25/07/18 00:47:35 GMT FROM: Mike Siegel at PSU/Swift MOC siegel@swift.psu.edu
M. H. Siegel (PSU), R. Gupta (NASA GSFC), S. Lanava (PSU), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB) and M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 00:14:02 UT, the Swift Burst Alert Telescope (BAT) triggered and located possible GRB 250718A (trigger=1334535). The BAT on-board calculated location is RA, Dec 241.998, -11.993 which is RA(J2000) = 16h 07m 59s Dec(J2000) = -11d 59' 35" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a sharp rise with a duration of just a few milliseconds. The peak count rate was ~1070 counts/sec (15-350 keV), at ~0 sec after the trigger.
Due to an observing constraint, Swift will not slew to the burst until 01:07 UT. Due to the marginal significance of the BAT image (6.85 sigma), and the lack of prompt XRT and UVOT data, this trigger may be due to a noise fluctuation. Further data are required to determine the nature of this trigger.
Burst Advocate for this burst is M. H. Siegel (siegel AT swift.psu.edu). 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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