GRB 200713A

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/)

P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 208 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 200713A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 76.94990, -32.81475 which is equivalent
to:

RA (J2000): 05h 07m 47.98s
Dec (J2000): -32d 48' 53.1"

with an uncertainty of 2.1 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.

M. Perri (ASDC), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Tohuvavohu
(U. Toronto), B. Sbarufatti (PSU), D.N. Burrows (PSU), K.L. Page (U.
Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester)
and A.Y. Lien report on behalf of the Swift-XRT team:

We have analysed 6.2 ks of XRT data for GRB 200713A (Lien et al. GCN
Circ. 28088
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 ), from 156 s to 62.7 ks after the  BAT trigger. The data
comprise 128 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Evans et al. (GCN Circ. 28089
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 ).

The light curve can be modelled with an initial power-law decay with an
index of alpha=5.1 (+/-0.3), followed by a break at T+358 s to an alpha
of 0.41 (+0.04, -0.05).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 3.71 (+0.26, -0.24). The
best-fitting absorption column is  3.2 (+/-0.5) x 10^21 cm^-2, in
excess of the Galactic value of 2.0 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.13 (+0.18, -0.17)
and a best-fitting absorption column of 1.7 (+/-0.5) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.2 x 10^-11 (4.5 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.7 (+/-0.5) x 10^21 cm^-2
Galactic foreground: 2.0 x 10^20 cm^-2
Excess significance: 5.0 sigma
Photon index:	     2.13 (+0.18, -0.17)

If the light curve continues to decay with a power-law decay index of
0.41, the count rate at T+24 hours will be 0.059 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.9 x
10^-12 (2.7 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00982201.

This circular is an official product of the Swift-XRT team.

T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU)
(i.e. the Swift-BAT team):

Using the data set from T-100 to T+963 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 200713A
(trigger #982201) (Lien et al., GCN Circ. 28088
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 ).
The BAT ground-calculated position is
RA, Dec = 76.941, -32.846 deg which is
   RA(J2000)  =  05h 07m 45.8s
   Dec(J2000) = -32d 50' 47.1"
with an uncertainty of 2.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 46%.

The mask-weighted light curve shows several weak overlapping pulses
that start at ~T+20 s and end at ~T+80 s. T90 (15-350 keV)
is 48.98 +- 9.52 sec (estimated error including systematics).

The time-averaged spectrum from T+18.45 to T+74.94 sec is best fit
by a simple power-law model.  The power law index of the time-averaged
spectrum is 2.48 +- 0.32.  The fluence in the 15-150 keV band
is 9.0 +- 1.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured
from T+49.94 sec in the 15-150 keV band is 0.8 +- 0.3 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/982201/BA/