GCN Circular 19761

F. E. Marshall (NASA/GSFC), P. D'Avanzo (INAF-OAB),
J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC), A. Melandri (INAF-OAB) and
M. H. Siegel (PSU) report on behalf of the Swift Team:

At 01:32:47 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 160804A (trigger= 707231 ).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 221.639, +10.001 which is 
   RA(J2000) =  14h 46m 33.4s
   Dec(J2000) = +10d 00m 03.6s
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty). 

The XRT began observing the field at 01:35:14 UT, 147 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 221.62909, +9.99599 which
is equivalent to:
   RA(J2000)  = 14h 46m 31.0s
   Dec(J2000) = +09d 59m 45.6s
with an uncertainty of 5 arcseconds (radius, 90% containment). This
location is 39 arcseconds from the BAT onboard position, within the BAT
error circle. 

Due to bad weather near Guam, we only have limited information about
this burst at this time. More information will be available after a
full ground station pass. 

Burst Advocate for this burst is F. E. Marshall (marshall AT milkyway.gsfc.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.)