TITLE:   GCN CIRCULAR
NUMBER:  8392
SUBJECT: Swift detection of a possible burst (trigger 332287)
DATE:    08/10/21 11:50:31 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

N. A. Lyons (U Leicester), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU),
J. R. Cummings (NASA/UMBC), P. A. Evans (U Leicester),
N. Gehrels (NASA/GSFC), O. Godet (U Leicester),
S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU),
J. A. Kennea (PSU), J. Mao (INAF-OAB), F. E. Marshall (NASA/GSFC),
P. T. O'Brien (U Leicester), K. L. Page (U Leicester),
B. Preger (ASDC), P. Romano (INAF-IASFPA), M. Stamatikos (NASA/ORAU),
R. L. C. Starling (U Leicester) and T. N. Ukwatta (GSFC/GWU) report on
behalf of the Swift Team:

At 11:20:26 UT, the Swift Burst Alert Telescope (BAT) triggered and
located trigger 332287.  Swift slewed immediately to the location. 
The BAT on-board calculated location is 
RA, Dec 301.006, +21.682 which is 
   RA(J2000)  =  20h 04m 02s
   Dec(J2000) = +21d 40' 57"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT TDRSS light curve shows a single spike
with a duration of about 0.4 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 11:21:29.7 UT, 62.9 seconds after
the BAT trigger. No source was detected in the promptly available XRT
data. We are waiting for the full dataset to detect and localise the
XRT counterpart. 

UVOT took a finding chart exposure of 250 seconds with the U filter
starting  63 seconds after the BAT trigger. No afterglow candidate
has been found in   the initial data products. The 2.7'x2.7'
sub-image covers 25% of the BAT  error circle, and the 8'x8' region
for the list of sources generated on-board  covers 100% of the BAT
error circle. Because of the high density of catalogued stars, 
the magnitude upper limit is difficult to determine. 

Burst Advocate for this burst is N. A. Lyons (nal14 AT star.le.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/too.html.)