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GCN Circular 16477

Subject
GRB 140629A: Swift detection of a burst with an optical counterpart
Date
2014-06-29T14:29:09Z (10 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC),
M. G. Bernardini (INAF-OAB), P. D'Avanzo (INAF-OAB),
J. A. Kennea (PSU) and K. L. Page (U Leicester) report on behalf of
the Swift Team:

At 14:17:30 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 140629A (trigger=602884).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 248.982, +41.890 which is 
   RA(J2000)  =  16h 35m 56s
   Dec(J2000) = +41d 53' 25"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows an initial rise of the event
starting at ~T-5 sec out to ~T+5 sec, at which point there is a gap in the
TDRSS light curve so nothing can be said at this time for the light curve
past T+5 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 14:19:04.5 UT, 94.2 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 248.97675, 41.87702 which
is equivalent to:
   RA(J2000)  = 16h 35m 54.42s
   Dec(J2000) = +41d 52' 37.3"
with an uncertainty of 4.0 arcseconds (radius, 90% containment). This
location is 48 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. No
spectrum from the promptly downlinked event data is yet available to
determine the column density. 

The initial flux in the 2.5 s image was 6.08e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 101 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  =	16:35:54.46 = 248.97691
  DEC(J2000) = +41:52:36.7  =  41.87685
with a 90%-confidence error radius of about 0.74 arc sec. This position is 0.8
arc sec. from the center of the XRT error circle. The estimated magnitude is
14.81 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.01. 

Burst Advocate for this burst is A. Y. Lien (yarleen AT gmail.com). 
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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