[vsnet-grb-info 18716] GRB 161109A: Swift-XRT observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20164
SUBJECT: GRB 161109A: Swift-XRT observations
DATE:    16/11/10 08:00:39 GMT
FROM:    Antonino D'Ai at IASF-PA  <antonino.dai at ifc.inaf.it>

S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo
(INAF-OAB), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N.
Burrows (PSU) and P.A. Evans (U. Leicester) report on behalf of the
Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 161109A (Desiante et al. GCN Circ. 20155)
in a series of observations tiled on the sky. The total exposure time
is 4.1 ks, distributed over 5 tiles; the maximum exposure at a single
sky location was 2.9 ks. The data were collected between T0+40.4 ks and
T0+63.6 ks, and are entirely in Photon Counting (PC) mode. 

Three uncatalogued X-ray sources have been detected, however none of
them is above the RASS limit or shows definitive signs of fading.
Therefore, at the present time we cannot identify which, if any, is the
afterglow. Details of these sources are given below:

Source 2:
  RA (J2000.0):  157.9051  =  10:31:37.24
  Dec (J2000.0): +61.8845  =  +61:53:04.4
  Error: 3.7 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (6.1 [+3.2, -2.4])e-3 ct s^-1   
  Distance: 244 arcsec from Fermi/LAT position.

Source 5:
  RA (J2000.0):  157.9726  =  10:31:53.43
  Dec (J2000.0): +61.9393  =  +61:56:21.6
  Error: 6.4 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (6.6 [+2.6, -2.1])e-3 ct s^-1   
  Distance: 471 arcsec from Fermi/LAT position.

Source 6:
  RA (J2000.0):  158.0653  =  10:32:15.66
  Dec (J2000.0): +61.6754  =  +61:40:31.5
  Error: 6.9 arcsec (radius, 90% conf.)
  Count-rate: (6.8 [+3.1, -2.4])e-3 ct s^-1   
  Distance: 635 arcsec from Fermi/LAT position.
  Flux: (2.01 [+0.91, -0.70])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Three catalogued sources were also detected.

The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at http://www.swift.ac.uk/xrt_products/TILED_GRB00060.

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