TITLE: GCN CIRCULAR NUMBER: 21016 SUBJECT: GRB 170419B: Swift detection of a burst DATE: 17/04/19 21:59:49 GMT FROM: Scott Barthelmy at NASA/GSFC A. Cholden-Brown (PSU), S. D. Barthelmy (GSFC), C. Gronwall (PSU), N. P. M. Kuin (UCL-MSSL), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 21:33:46 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170419B (trigger=748947). Swift did not slew due to Sun constraint. The BAT on-board calculated location is RA, Dec 60.498, -15.143, which is RA(J2000) = 04h 01m 59s Dec(J2000) = -15d 08' 32" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single with a duration of about 10 sec. The peak count rate was ~3000 counts/sec (15-350 keV), at ~3 sec after the trigger. Due to a Sun observing constraint, Swift cannot slew to the BAT position until 05:29 UT on 2017 June 19. There will thus be no XRT or UVOT data for this trigger before this time. Burst Advocate for this burst is A. Cholden-Brown (aaronb 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/too.html.)