GCN Circular 10177

V. D'Elia, G. Stratta, M. Perri (ASDC), P.A. Evans and M.R. Goad (U.  
Leicester),
J. Cummings (GSFC/CRESST), S. Campana (INAF-OAB) report on behalf of  
the Swift-XRT team:

We have analysed 3.85 ks of XRT data for GRB 091117 (Cummings et al.  
et al.
GCN Circ. 10171
Not found
 
 
), from 96765 s to 119.4 ks after the Suzaku trigger. The
data are entirely in Photon Counting (PC) mode. Two sources are detected
at the edge of the BAT error circle.

Source #1:
using 722 s of XRT Photon Counting mode data and 1 UVOT
images, we find an astrometrically corrected X-ray position (using the
XRT-UVOT alignment and matching UVOT field sources to the USNO-B1
catalogue): RA, Dec = 30.97240, -16.97490 deg which is equivalent to:

RA (J2000):  02 03 53.38
Dec (J2000): -16 58 29.8

with an uncertainty of 3.6 arcsec (radius, 90% confidence).

This position may be improved as more data are received.  The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

The source is at a count rate level of (4.8+/-1.4)e-3 counts/s.
The light curve does not allow us to assess if the source is fading.

This source has been reported by Berger et al. (GCN Circ. 10173
Not found
 
 
)
to be coincident with the DSS galaxy APMUKS B020129.84-171252.3
at redshift z=0.096 (Chornock & Berger 2009, GCN Circ. 10176
Not found
 
 
)
We can't distinguish if this is nuclear emission from the AGN
discussed by Berger et al. (GCN Circ. 10176
Not found
 
 
)

Source #2:
the other source has a count rate level of
(2.7+/-1.1)e-3 counts/s and is at RA, Dec= 30.988333, -16.948583 deg
which is equivalent to

RA (J2000): 02 03 57.2
Dec(J2000): -16 56 54.9

with an uncertainty of 7.7 arcsec (radius, 90% confidence).

The light curve does not allow us to assess if the source is fading.

We note that there is a known source (2MASX J02035665-1656585 at  
z=0.096220)
located 8.8 arcsec from Source #2.

Further observations are planned for this field.

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