[vsnet-grb-info 5429] GRB 071117: Swift-XRT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7103
SUBJECT: GRB 071117: Swift-XRT refined analysis
DATE:    07/11/17 23:01:27 GMT
FROM:    Cristiano Guidorzi at INAF-OAB  <cristiano.guidorzi at brera.inaf.it>

C. Guidorzi, P. Romano (Univ. Bicocca & INAF-OAB),
A. Moretti (INAF-OAB) and T.N. Ukwatta (GSFC/GWU),
report on behalf of the Swift-XRT team:

Swift XRT observed the GRB 071117 (trigger=296805, Ukwatta et al., GCN
Circ. 7098) beginning 2.8 ks after the BAT trigger.
In 4.4 ks of Photon Counting mode data spanning 2.8-14.7 ks after
the trigger the position of the X-ray afterglow is
RA,Dec =335.04579,-63.44278 degrees, which corresponds to

RA(J2000) =  22 20 10.99
Dec(J2000)= -63 26 34.0

with error circle of radius 3.8 arcsec (90%, including
boresight uncertainties). This lies 3.6 arcsec from the previous
XRT position (Romano et al., GCN Circ. 7100) and 32 arcsec from
the BAT refined position (Krimm et al., GCN Circ 7102).

The X-ray light curve can be fit by a power law from
T+2.8ks to T+14.7ks, with a decay index of 0.8 +/- 0.2.

The Photon Counting spectrum can modelled with an absorbed power-law, with
a photon index of 2.2 +0.4/-0.3 and a total absorbing column of NH = (2.3
+0.9/-0.8) e21 cm-2. The Galactic value is 2.3e20 cm-2 in the direction
of the burst. The 0.3-10 keV observed (unabsorbed) flux during this time
is 3.0e-12 (5.0e-12) erg cm-2 s-1. Uncertainties are given at 90% 
confidence.

Assuming the source continues to decay with the same rate,
we predict an XRT count rate of 1.3e-2 counts/s at T+24 hours, which
corresponds to an observed 0.3-10keV flux of 7.8e-13 ergs cm-2 s-1.

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