[vsnet-grb-info 5372] GRB 071109: further Swift-XRT analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7053
SUBJECT: GRB 071109: further Swift-XRT analysis
DATE:    07/11/10 19:05:09 GMT
FROM:    Matteo Perri at ISAC/ASDC  <perri at asdc.asi.it>

M. Perri, G. Stratta (ASDC) and D.N. Burrows (PSU) report on behalf of
the Swift-XRT team:

We have analysed a further 4.9 ks of Swift-XRT Photon Counting mode data
of the field of the INTEGRAL burst GRB 071109 (Mereghetti et al.,
GCN Circ. 7046), beginning ~5 hours after the INTEGRAL trigger.

The possible afterglow candidate reported in GCN Circ. 7050 (Perri et al.)
is detected also in this second image with a count rate of (2.4 +/-0.8)e-3
cts/s and thus is consistent with being constant between the two
observations. We note that this X-ray source lies 3.7 arcmin from the
INTEGRAL position and outside its 2.5 arcmin error circle.

In the total Photon Counting mode exposure of 9.7 ks we did not detect
any X-ray source within the INTEGRAL error circle (Mereghetti et al.,
GCN Circ. 7046) or at the position of the  VLA radio source reported in
GCN Circ. 7049 (Chandra & Frail). We estimate a three sigma upper limit
on the count rate of about 1.5e-3 cts/s. Assuming a power-law spectrum
with
photon index Gamma=2 and a Galactic column of 2.5e21 cm-2, this
corresponds
to an upper limit on the observed flux of ~7e-14 ergs/cm2/s (0.3-10 keV).

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