[vsnet-grb-info 26050] GRB 200714E: Swift-XRT afterglow detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28150
SUBJECT: GRB 200714E: Swift-XRT afterglow detection
DATE:    20/07/21 15:18:10 GMT
FROM:    Phil Evans at U of Leicester  <pae9 at leicester.ac.uk>

V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), B. Sbarufatti (PSU), D.N.
Burrows (PSU), J. D. Gropp (PSU), A.P. Beardmore (U. Leicester), J.P.
Osborne (U. Leicester), A. Melandri (INAF-OAB) and P.A. Evans (U.
Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has conducted further observations of the field of the
Swift/BAT-GUANO-detected burst GRB 200714E (Tohuvavohu et al. GCN Circ.
28103). The observations now extend from T0+37.4 ks to T0+578.8 ks. The
source previously reported by D'Elia et al. (GCN Circ. 28107), "Source
1", is fading with 3-sigma significance, and is therefore likely the
GRB afterglow. Using 4152 s of PC mode data and 4 UVOT images, we find
an enhanced XRT position (using the XRT-UVOT alignment and matching
UVOT field sources to the USNO-B1 catalogue): RA, Dec = 196.82291,
-51.63937 which is equivalent to:

RA (J2000): 13h 07m 17.50s
Dec(J2000): -51d 38' 21.7"

with an uncertainty of 2.2 arcsec (radius, 90% confidence). This
position is 95 arcsec from the Swift/BAT position.  The source is
fading with alpha >0.5.

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.6 (+0.6, -0.3). The
best-fitting absorption column is  consistent with the Galactic value
of 3.1 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum  is 4.6 x 10^-11 (5.6 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     3.1 (+/-2.2) x 10^21 cm^-2
Galactic foreground: 3.1 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.6 (+0.6, -0.3)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00021017.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021017.

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