[vsnet-grb-info 15289] GRB 140713A: Swift detection of a burst

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16581
SUBJECT: GRB 140713A: Swift detection of a burst
DATE:    14/07/13 18:58:44 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at milkyway.gsfc.nasa.gov>

V. Mangano (PSU), S. D. Barthelmy (GSFC), M. M. Chester (PSU),
J. R. Cummings (NASA/UMBC), J. A. Kennea (PSU) and
B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team:

At 18:43:45 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 140713A (trigger=604232).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 281.114, +59.625 which is 
   RA(J2000)  =  18h 44m 27s
   Dec(J2000) = +59d 37' 29"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows two peaks
with a total duration of about 7 sec.  The peak count rate
was ~3500 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 18:44:57.8 UT, 72.8 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 281.1053, 59.6333 which
is equivalent to:
   RA(J2000)  = 18h 44m 25.28s
   Dec(J2000) = +59d 37' 59.8"
with an uncertainty of 2.0 arcseconds (radius, 90% containment). This
location is 33 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.  We
cannot determine whether the source is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (4.97 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 7.8
(+5.23/-4.19) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 76 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. 
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 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.05. 

Burst Advocate for this burst is V. Mangano (vxm22 AT psu.edu). 
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.)