[vsnet-grb-info 2467] GRB051117B: Swift XRT refined analysis

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4304
SUBJECT: GRB051117B: Swift XRT refined analysis
DATE:    05/11/25 16:39:23 GMT
FROM:    Andy Beardmore at U Leicester  <apb at star.le.ac.uk>

A.P. Beardmore, K.L. Page (U. Leicester), K. Hurley (Berkeley),
M. Chester (PSU) report on behalf of the Swift XRT team.

We report on further analysis of the XRT observation of GRB051117B.
By fitting the XRT point spread function to 8ks of PC mode data obtained
from the first observation segment, we find the following revised
position:

RA(J2000) =   05:40:43.0
Dec(J2000) = -19:16:26.5

with an uncertainty of 3.4 arcsec (90% containment).
This includes the latest XRT boresight correction.

The XRT 0.2-10keV light curve shows a simple power-law decay with a
slope of 1.75 +/- 0.25 out to T+12.8ks. After this time the source was
no longer detected, with a 3 sigma upper limit to the count rate of
2.7e-4 count/s in an exposure of 85ks.

An absorbed power-law fit to the photon counting mode spectrum from
T+149s to T+12.8ks gave a photon index 1.9 +1.1/-0.6 and a column
density of (0.4 +0.7/-0.2)e22 cm**2. The Galactic column in this
direction is 4.5E+20 cm**2. The unabsorbed 0.2-10keV flux was
1.4e-12 ergs cm**-2 s**-1.