[vsnet-grb-info 8793] GRB 091117: Swift-XRT late time observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  10292
SUBJECT: GRB 091117: Swift-XRT late time observations
DATE:    09/12/23 16:17:58 GMT
FROM:    Valerio D'Elia at INAF-OAR  <delia at mporzio.astro.it>

V. D'Elia, G. Stratta, M. Perri (ASDC), J. Cummings (GSFC/CRESST) report
on behalf of the Swift-XRT team:

Swift-XRT has observed the field of GRB 091117 about one month after  
the burst
(Cummings et al. GCN Circ. 10171).   The data set consists of two  
further
observations, 9.7 ks and 9.2 ks, from 32.8 to 34.2 days after the  
trigger.
The data are entirely in Photon Counting (PC) mode.

We found that Source #1 (Berger, GCN Circ. 10173; D'Elia et al.,
GCN Circ. 10177; Fox, GCN Circ. 10179, D'Elia et al., GCN Circ 10181)
is still detected with a count rate of (2.95+/-0.70)e-3 cts/s (first
observation) and (3.42+/-0.75)e-3 cts/s (second observation),
thus showing no evidence of fading with respect to the first Swift
follow-up observations.  Thus evidence of possible fading of Source #1,
reported in Fox (GCN Circ. 10179), D'Elia et al. (GCN Circ.10181) and
Fox & Berger (GCN Circ. 10232), is not confirmed by these measurements.

Source #2 (D'Elia et al., GCN Circ. 10177; Fox, GCN Circ. 10179,  
D'Elia et al.,
GCN Circ 10181) is also detected, and the derived count rate is
(2.03+/-0.55)e-3 cts/s (first observation) and (1.85+/-0.54)e-3 cts/s
(second observation).  No evidence of a fading behavior is found for  
this
source either.

All quoted errors are given at the 1-sigma level.

In view of these XRT observations, we can safely conclude that neither
source is the X-ray afterglow of GRB091117.

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