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GCN Circular 16202

Subject
GRB 140502A: Swift detection of a burst
Date
2014-05-02T08:44:00Z (10 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
C. A. Swenson (PSU), S. D. Barthelmy (GSFC), M. M. Chester (PSU) and
P. A. Evans (U Leicester) report on behalf of the Swift Team:

At 08:30:20 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 140502A (trigger=597841).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 319.155, +49.018 which is 
   RA(J2000)  =  21h 16m 37s
   Dec(J2000) = +49d 01' 04"
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 25 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 08:31:31.3 UT, 70.8 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 319.18744, 48.97012 which is equivalent
to:
   RA(J2000)  = 21h 16m 44.99s
   Dec(J2000) = +48d 58' 12.4"
with an uncertainty of 4.0 arcseconds (radius, 90% containment). This
location is 188 arcseconds from the BAT onboard position, outside 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 gives a column density consistent with the Galactic value of 9.47
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 74 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 none of
the XRT error circle. 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 large, but
uncertain extinction expected. 

Burst Advocate for this burst is C. A. Swenson (cswenson AT astro.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.)
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