TITLE: GCN CIRCULAR NUMBER: 25368 SUBJECT: GRB 190816A: Swift detection of a burst DATE: 19/08/16 14:56:49 GMT FROM: Scott Barthelmy at NASA/GSFC K. L. Page (U Leicester), S. D. Barthelmy (GSFC), P. A. Evans (U Leicester), J.D. Gropp (PSU), N. J. Klingler (PSU), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), M. J. Moss (GWU), D. M. Palmer (LANL) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 14:42:24 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 190816A (trigger=920783). Swift did not slew due to an observing constraint. The BAT on-board calculated location is RA, Dec 341.193, -29.740, which is RA(J2000) = 22h 44m 46s Dec(J2000) = -29d 44' 23" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a couple peaks with a total duration of about 30 sec. The peak count rate was ~600 counts/sec (15-350 keV), at ~3 sec after the trigger. Due to a Moon observing constraint, Swift cannot slew to the BAT position until 17:11 UT on 2019 August 17. There will thus be no XRT or UVOT data for this trigger before this time. Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk). 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/)