GCN Circular 10292
Subject
GRB 091117: Swift-XRT late time observations
Date
2009-12-23T16:17:58Z (15 years ago)
From
Valerio D'Elia at INAF-OAR <delia@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.