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GCN Circular 12196

GRB 110726A: Swift detection of a burst
2011-07-26T01:48:27Z (13 years ago)
Scott Barthelmy at NASA/GSFC <>
C. A. Wolf (PSU), S. D. Barthelmy (GSFC),
S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU),
O. M. Littlejohns (U Leicester), C. B. Markwardt (NASA/GSFC),
A. Melandri (INAF-OAB), C. J. Mountford (U Leicester),
D. M. Palmer (LANL), T. Sakamoto (NASA/UMBC), C. J. Saxton (UCL-MSSL),
M. H. Siegel (PSU), E. Sonbas (GSFC/USRA/Adiyaman Univ.),
M. Stamatikos (OSU/NASA/GSFC), C. A. Swenson (PSU) and
E. Troja (NASA/GSFC/ORAU) report on behalf of the Swift Team:

At 01:30:40 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 110726A (trigger=458059).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 286.751, +56.053 which is 
   RA(J2000)  =  19h 07m 00s
   Dec(J2000) = +56d 03' 12"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single peak
with a duration of about 10 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 01:31:38.7 UT, 58.2 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 286.7161,
56.0712 which is equivalent to:
   RA(J2000)  = 19h 06m 51.87s
   Dec(J2000) = +56d 04' 16.3"
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 95 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 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (5.60 x
10^20 cm^-2, Kalberla et al. 2005), with an excess column of 1.8
(+1.73/-1.55) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White
filter  starting 59 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 19.6 mag.   No correction has been
made for the expected extinction corresponding to  E(B-V) of 0.08. 

Burst Advocate for this burst is C. A. Wolf (cwolf AT 
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:
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