TITLE:   GCN CIRCULAR
NUMBER:  43671
SUBJECT: GRB 260208B: Swift-XRT observations
DATE:    26/02/09 16:03:40 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo
(INAF-OAB), M.G. Bernardini (INAF-OAB), E. Ambrosi  (INAF-IASFPA), J.A.
Kennea (PSU), D.N. Burrows (PSU), S. Lanava (PSU) and P.A. Evans (U.
Leicester) reports on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 260208B, collecting  1.6 ks of Photon
Counting (PC) mode data between T0+33.1 ks and T0+44.4 ks. 

One uncatalogued X-ray source has been detected within the estimated
3-sigma Fermi/LAT error region (354 arcsec), it is below the RASS limit
and shows no definitive signs of fading. Details of this source are
given below:

Source 1:
  RA (J2000.0):  99.6189  =  06h 38m 28.55s
  Dec (J2000.0): -13.7743  =  -13d 46' 27.4"
  Error: 3.1 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: 0.0338 +/- 0.0067 ct s^-1   
  Distance: 238 arcsec from Fermi/LAT position.
  Flux: (1.63 +/- 0.32)e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV)

The flux reported by EP-WXT for this source at 74.7 ks after the
trigger (GCN Circ. 43663) is about a factor of 10 fainter than this XRT
measurement, however, which suggests it is indeed the GRB afterglow.

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/00021909. We note that the large
number of spurious sources was due to unusually high background.

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