TITLE:   GCN CIRCULAR
NUMBER:  8270
SUBJECT: GRB 080919: Swift detection of a short burst
DATE:    08/09/19 00:41:17 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

B. Preger (ASDC), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),
J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC),
S. T. Holland (CRESST/USRA/GSFC), S. D. Hunsberger (PSU),
S. Immler (CRESST/GSFC/UMD), H. A. Krimm (CRESST/GSFC/USRA),
C. B. Markwardt (CRESST/GSFC/UMD), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL), M. Perri (ASDC), T. Sakamoto (NASA/UMBC),
M. Stamatikos (NASA/ORAU), G. Stratta (ASDC), M. C. Stroh (PSU) and
T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:

At 00:05:13 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 080919 (trigger=325268).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 265.289, -42.396 which is 
   RA(J2000)  =  17h 41m 09s
   Dec(J2000) = -42d 23' 45"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single spike
with a duration of about 1 sec.  The peak count rate
was ~3300 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 00:06:23.8 UT, 70.8 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 265.22379,
-42.36876 which is equivalent to:
   RA(J2000)  = 17h 40m 53.71s
   Dec(J2000) = -42d 22' 07.5"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This
location is 199 arcseconds from the BAT onboard position, outside the
BAT error circle. 

UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm)
filter starting 82 seconds after the BAT trigger.  The 2.7'x2.7' sub-image 
covers 25% of the BAT error circle and none of the XRT error circle. 
The 8'x8' region for the list of sources generated on-board covers 90% of the 
BAT error circle and 100% of the XRT error circle. 
No afterglow candidate has been found in the initial data products. Typical
upper limit is ~18th magitude. No correction has been made for the expected
extinction corresponding to E(B-V) of 0.49. We note that this is a crowded field. 

This event lies near to the direction of the Galactic Bulge
(long,lat = 348.03, -6.26) and so we cannot immediately rule out
the possibility that this source is Galactic.  However, the duration
and the spectral hardness of this event are consistent with a
classical Short GRB. 

Burst Advocate for this burst is B. Preger (preger AT asdc.asi.it). 
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.)