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GCN Circular 12158

Subject
GRB 110715A: Swift detection of a bright burst with an optical counterpart
Date
2011-07-15T13:26:17Z (13 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
E. Sonbas (GSFC/USRA/Adiyaman Univ.), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),
D. N. Burrows (PSU), V. D'Elia (ASDC), M. De Pasquale (UCL-MSSL),
P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC),
C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC),
J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),
N. P. M. Kuin (UCL-MSSL), O. M. Littlejohns (U Leicester),
F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester),
S. R. Oates (UCL-MSSL), C. Pagani (U Leicester),
K. L. Page (U Leicester), P. Romano (INAF-IASFPA),
A. Rowlinson (U Leicester), T. Sakamoto (NASA/UMBC),
M. H. Siegel (PSU), G. Stratta (ASDC), C. A. Swenson (PSU) and
E. Troja (NASA/GSFC/ORAU) report on behalf of the Swift Team:

At 13:13:50 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 110715A (trigger=457330).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 237.660, -46.233 which is 
   RA(J2000) = 15h 50m 38s
   Dec(J2000) = -46d 13' 59"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a double-peaked
structure with a duration of about 15 sec.  The peak count rate
was ~70,000 counts/sec (15-350 keV), at ~2 sec after the trigger. 

The XRT began observing the field at 13:15:21.9 UT, 90.9 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 237.6832, -46.2326 which is equivalent to:
   RA(J2000)  = 15h 50m 43.96s
   Dec(J2000) = -46d 13' 57.3"
with an uncertainty of 5.8 arcseconds (radius, 90% containment). This
location is 57 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy. 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 99 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  =	15:50:44.09 = 237.68370
  DEC(J2000) = -46:14:06.5  = -46.23513
with a 90%-confidence error radius of about 0.62 arc sec. This position is 9.2
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.34 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.59. 

Burst Advocate for this burst is E. Sonbas (eda.sonbas AT 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.)
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