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GCN Circular 12088

Subject
GRB 110625A: Swift detection of a burst
Date
2011-06-25T21:25:19Z (13 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
K. L. Page (U Leicester), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), J. R. Cummings (NASA/UMBC),
V. D'Elia (ASDC), S. T. Holland (CRESST/USRA/GSFC),
F. E. Marshall (NASA/GSFC), C. Pagani (U Leicester),
D. M. Palmer (LANL), P. Romano (INAF-IASFPA), C. J. Saxton (UCL-MSSL),
M. H. Siegel (PSU), M. C. Stroh (PSU) and T. N. Ukwatta (MSU) report
on behalf of the Swift Team:

At 21:08:28 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 110625A (trigger=456073).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 286.750, +6.753, which is 
   RA(J2000)  =  19h 07m 00s
   Dec(J2000) = +06d 45' 10"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows several bright peaks
with a total duration of about 60 sec.  The peak count rate
was ~20,000 counts/sec (15-350 keV), at ~13 sec after the trigger. 

The XRT began observing the field at 21:10:48.8 UT, 140.3 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 286.73189, 6.75386
which is equivalent to:
   RA(J2000)  = 19h 06m 55.65s
   Dec(J2000) = +06d 45' 13.9"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 64 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data does not constrain the column density. 

The initial flux in the 2.5 s image was 1.72e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 250 seconds with the U filter starting
205 seconds after the BAT trigger. No credible afterglow candidate has been
found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the
XRT error circle. The typical 3-sigma upper limit has been about 19.2 mag. The
8'x8' region for the list of sources generated on-board covers 100% of the XRT
error circle. The list of sources is typically complete to about 18.0 mag. No
correction has been made for the large, but uncertain extinction expected. 

Burst Advocate for this burst is K. L. Page (kpa 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.)
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