TITLE:   GCN CIRCULAR
NUMBER:  21666
SUBJECT: GRB 170823A: Swift detection of a burst
DATE:    17/08/23 22:30:42 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

E. Troja (NASA/GSFC/UMCP), A. D'Ai (INAF-IASFPA), V. D'Elia (ASDC),
K. L. Page (U Leicester) and A. Tohuvavohu (PSU) report on behalf of
the Swift Team:

At 22:16:48 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170823A (trigger=769177).  Swift did not slew due to the Sun 
observing constraint. The BAT on-board calculated location is 
RA, Dec 188.719, +35.582 which is 
   RA(J2000) = 12h 34m 53s
   Dec(J2000) = +35d 34' 55"
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 60 sec.  The peak count rate
was ~4900 counts/sec (15-350 keV), at ~11 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 18:03 UT on 2017 October 17. There will thus be no XRT
or UVOT data for this trigger before this time. 

Burst Advocate for this burst is E. Troja (eleonora.troja AT nasa.gov). 
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.)