TITLE:   GCN CIRCULAR
NUMBER:  28088
SUBJECT: GRB 200713A: Swift detection of a burst
DATE:    20/07/13 12:05:03 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

A. Y. Lien (GSFC/UMBC), E. Ambrosi (INAF-IASFPA),
S. D. Barthelmy (GSFC), V. D'Elia (SSDC), J.D. Gropp (PSU),
N. J. Klingler (PSU), S. Laha (GSFC/UMBC/CRESST),
K. L. Page (U Leicester) and A. Tohuvavohu (U Toronto) report on
behalf of the Neil Gehrels Swift Observatory Team:

At 11:42:54 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 200713A (trigger=982201).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 76.962, -32.825, which is 
   RA(J2000)  =  05h 07m 51s
   Dec(J2000) = -32d 49' 30"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is the usual for image triggers, the light curve
does not show anything. 

The XRT began observing the field at 11:45:24.7 UT, 150.1 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
76.9492, -32.8144 which is equivalent to:
   RA(J2000)  = 05h 07m 47.81s
   Dec(J2000) = -32d 48' 51.7"
with an uncertainty of 2.7 arcseconds (radius, 90% containment). This
location is 54 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 https://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 1.99
x 10^20 cm^-2 (Willingale et al. 2013). 

The initial flux in the 2.5 s image was 1.27e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 159 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
0.02. 

Burst Advocate for this burst is A. Y. Lien (amy.y.lien 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/)