TITLE: GCN CIRCULAR NUMBER: 18225 SUBJECT: GRB 150901A: Swift detection of a burst DATE: 15/09/01 15:40:23 GMT FROM: Scott Barthelmy at NASA/GSFC B. Sbarufatti (INAF-OAB/PSU), S. D. Barthelmy (GSFC), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA) and T. N. Ukwatta (LANL) report on behalf of the Swift Team: At 15:26:35 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 150901A (trigger=654042). Swift did not slew due Sun observing constraint. The BAT on-board calculated location is RA, Dec 183.586, +25.038, which is RA(J2000) = 12h 14m 21s Dec(J2000) = +25d 02' 19" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peak with a duration of about 25 sec. The peak count rate was ~700 counts/sec (15-350 keV), at ~1 sec after the trigger. Due to a Sun observing constraint, Swift cannot slew to the BAT position until 00:01 UT on 2015 October 28. There will thus be no XRT or UVOT data for this trigger before this time. Burst Advocate for this burst is B. Sbarufatti (boris.sbarufatti AT brera.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/too.html.)